Curriculum›4B›Chapter 15

Chapter 15: worked solutions and marking guide

37 review answers and 37 exam answers

Chapter review solutions

Question 1 · classification

Classify a 180° angle as acute, right, obtuse, or straight.

180°
Answer: straight

Compare 180° to 90° and 180°. A ray length does not affect the turn.

Question 2 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 165°

Align the protractor at the vertex and read from the baseline: 165°.

Question 3 · construction

Using a protractor, construct an angle measuring 85°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 85° angle with labeled rays

Check placement of the center and zero baseline; mark 85°, draw second ray, and label.

85°
Question 4 · angle arithmetic

An angle of 27° lies next to another angle on a straight line. Find the missing angle.

Answer: 153°

Adjacent angles along a straight line add to 180°. Subtract 27 from 180.

Question 5 · reflex angle

The smaller angle between two rays is 72°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 288°

Reflex angle = 360°−72°=288°. Mark the outside turn.

Question 6 · classification

Classify a 100° angle as acute, right, obtuse, or straight.

100°
Answer: obtuse

Compare 100° to 90° and 180°. A ray length does not affect the turn.

Question 7 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 135°

Align the protractor at the vertex and read from the baseline: 135°.

Question 8 · construction

Using a protractor, construct an angle measuring 25°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 25° angle with labeled rays

Check placement of the center and zero baseline; mark 25°, draw second ray, and label.

25°
Question 9 · angle arithmetic

An angle of 149° lies next to another angle on a straight line. Find the missing angle.

Answer: 31°

Adjacent angles along a straight line add to 180°. Subtract 149 from 180.

Question 10 · reflex angle

The smaller angle between two rays is 82°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 278°

Reflex angle = 360°−82°=278°. Mark the outside turn.

Question 11 · classification

Classify a 145° angle as acute, right, obtuse, or straight.

145°
Answer: obtuse

Compare 145° to 90° and 180°. A ray length does not affect the turn.

Question 12 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 75°

Align the protractor at the vertex and read from the baseline: 75°.

Question 13 · construction

Using a protractor, construct an angle measuring 70°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 70° angle with labeled rays

Check placement of the center and zero baseline; mark 70°, draw second ray, and label.

70°
Question 14 · angle arithmetic

An angle of 80° lies next to another angle on a straight line. Find the missing angle.

Answer: 100°

Adjacent angles along a straight line add to 180°. Subtract 80 from 180.

Question 15 · reflex angle

The smaller angle between two rays is 83°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 277°

Reflex angle = 360°−83°=277°. Mark the outside turn.

Question 16 · classification

Classify a 135° angle as acute, right, obtuse, or straight.

135°
Answer: obtuse

Compare 135° to 90° and 180°. A ray length does not affect the turn.

Question 17 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 150°

Align the protractor at the vertex and read from the baseline: 150°.

Question 18 · construction

Using a protractor, construct an angle measuring 35°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 35° angle with labeled rays

Check placement of the center and zero baseline; mark 35°, draw second ray, and label.

35°
Question 19 · angle arithmetic

An angle of 102° lies next to another angle on a straight line. Find the missing angle.

Answer: 78°

Adjacent angles along a straight line add to 180°. Subtract 102 from 180.

Question 20 · reflex angle

The smaller angle between two rays is 164°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 196°

Reflex angle = 360°−164°=196°. Mark the outside turn.

Question 21 · classification

Classify a 70° angle as acute, right, obtuse, or straight.

70°
Answer: acute

Compare 70° to 90° and 180°. A ray length does not affect the turn.

Question 22 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 105°

Align the protractor at the vertex and read from the baseline: 105°.

Question 23 · construction

Using a protractor, construct an angle measuring 140°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 140° angle with labeled rays

Check placement of the center and zero baseline; mark 140°, draw second ray, and label.

140°
Question 24 · angle arithmetic

An angle of 71° lies next to another angle on a straight line. Find the missing angle.

Answer: 109°

Adjacent angles along a straight line add to 180°. Subtract 71 from 180.

Question 25 · reflex angle

The smaller angle between two rays is 57°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 303°

Reflex angle = 360°−57°=303°. Mark the outside turn.

Question 26 · classification

Classify a 15° angle as acute, right, obtuse, or straight.

15°
Answer: acute

Compare 15° to 90° and 180°. A ray length does not affect the turn.

Question 27 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 110°

Align the protractor at the vertex and read from the baseline: 110°.

Question 28 · construction

Using a protractor, construct an angle measuring 115°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 115° angle with labeled rays

Check placement of the center and zero baseline; mark 115°, draw second ray, and label.

115°
Question 29 · angle arithmetic

An angle of 77° lies next to another angle on a straight line. Find the missing angle.

Answer: 103°

Adjacent angles along a straight line add to 180°. Subtract 77 from 180.

Question 30 · reflex angle

The smaller angle between two rays is 31°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 329°

Reflex angle = 360°−31°=329°. Mark the outside turn.

Question 31 · classification

Classify a 155° angle as acute, right, obtuse, or straight.

155°
Answer: obtuse

Compare 155° to 90° and 180°. A ray length does not affect the turn.

Question 32 · measurement

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 160°

Align the protractor at the vertex and read from the baseline: 160°.

Question 33 · reasoning

Classify a 95° angle as acute, right, obtuse, or straight. Explain which turn or benchmark you used.

95°
Answer: obtuse

Compare 95° to 90° and 180°. A ray length does not affect the turn. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Question 34 · reasoning

Measure the smaller indicated angle between the two rays, in degrees. Explain which turn or benchmark you used.

?°
Answer: 70°

Align the protractor at the vertex and read from the baseline: 70°. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Question 35 · reasoning

Using a protractor, construct an angle measuring 75°. Label its vertex and both rays. Explain which turn or benchmark you used.

Use the space to draw both rays
Answer: A correctly constructed 75° angle with labeled rays

Check placement of the center and zero baseline; mark 75°, draw second ray, and label. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

75°
Question 36 · reasoning

An angle of 114° lies next to another angle on a straight line. Find the missing angle. Explain which turn or benchmark you used.

Answer: 66°

Adjacent angles along a straight line add to 180°. Subtract 114 from 180. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Question 37 · reasoning

The smaller angle between two rays is 31°. Find their reflex angle. Explain which turn or benchmark you used.

?°Reflex turn: use the outside region
Answer: 329°

Reflex angle = 360°−31°=329°. Mark the outside turn. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Practice examination solutions

Question 1 · construction · 4 points

Using a protractor, construct an angle measuring 105°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 105° angle with labeled rays

Check placement of the center and zero baseline; mark 105°, draw second ray, and label.

105°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 2 · angle arithmetic · 2 points

An angle of 116° lies next to another angle on a straight line. Find the missing angle.

Answer: 64°

Adjacent angles along a straight line add to 180°. Subtract 116 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 3 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 95°

Align the protractor at the vertex and read from the baseline: 95°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 4 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 40°

Align the protractor at the vertex and read from the baseline: 40°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 5 · classification · 2 points

Classify a 60° angle as acute, right, obtuse, or straight.

60°
Answer: acute

Compare 60° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 6 · angle arithmetic · 2 points

An angle of 26° lies next to another angle on a straight line. Find the missing angle.

Answer: 154°

Adjacent angles along a straight line add to 180°. Subtract 26 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 7 · reasoning · 3 points

The smaller angle between two rays is 163°. Find their reflex angle. Explain which turn or benchmark you used.

?°Reflex turn: use the outside region
Answer: 197°

Reflex angle = 360°−163°=197°. Mark the outside turn. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Scoring (3 points): 1 point for identifying the relevant property; 1 for a correct solution; 1 for reasoning.

Question 8 · reasoning · 3 points

Classify a 170° angle as acute, right, obtuse, or straight. Explain which turn or benchmark you used.

170°
Answer: obtuse

Compare 170° to 90° and 180°. A ray length does not affect the turn. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Scoring (3 points): 1 point for identifying the relevant property; 1 for a correct solution; 1 for reasoning.

Question 9 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 30°

Align the protractor at the vertex and read from the baseline: 30°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 10 · construction · 4 points

Using a protractor, construct an angle measuring 55°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 55° angle with labeled rays

Check placement of the center and zero baseline; mark 55°, draw second ray, and label.

55°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 11 · angle arithmetic · 2 points

An angle of 105° lies next to another angle on a straight line. Find the missing angle.

Answer: 75°

Adjacent angles along a straight line add to 180°. Subtract 105 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 12 · reflex angle · 2 points

The smaller angle between two rays is 133°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 227°

Reflex angle = 360°−133°=227°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 13 · reflex angle · 2 points

The smaller angle between two rays is 71°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 289°

Reflex angle = 360°−71°=289°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 14 · reflex angle · 2 points

The smaller angle between two rays is 147°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 213°

Reflex angle = 360°−147°=213°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 15 · reasoning · 3 points

Measure the smaller indicated angle between the two rays, in degrees. Explain which turn or benchmark you used.

?°
Answer: 90°

Align the protractor at the vertex and read from the baseline: 90°. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Scoring (3 points): 1 point for identifying the relevant property; 1 for a correct solution; 1 for reasoning.

Question 16 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 45°

Align the protractor at the vertex and read from the baseline: 45°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 17 · classification · 2 points

Classify a 105° angle as acute, right, obtuse, or straight.

105°
Answer: obtuse

Compare 105° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 18 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 125°

Align the protractor at the vertex and read from the baseline: 125°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 19 · classification · 2 points

Classify a 160° angle as acute, right, obtuse, or straight.

160°
Answer: obtuse

Compare 160° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 20 · construction · 4 points

Using a protractor, construct an angle measuring 150°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 150° angle with labeled rays

Check placement of the center and zero baseline; mark 150°, draw second ray, and label.

150°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 21 · angle arithmetic · 2 points

An angle of 42° lies next to another angle on a straight line. Find the missing angle.

Answer: 138°

Adjacent angles along a straight line add to 180°. Subtract 42 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 22 · reasoning · 3 points

Using a protractor, construct an angle measuring 40°. Label its vertex and both rays. Explain which turn or benchmark you used.

Use the space to draw both rays
Answer: A correctly constructed 40° angle with labeled rays

Check placement of the center and zero baseline; mark 40°, draw second ray, and label. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

40°

Scoring (3 points): 1 point for identifying the relevant property; 1 for a correct solution; 1 for reasoning.

Question 23 · reasoning · 3 points

An angle of 112° lies next to another angle on a straight line. Find the missing angle. Explain which turn or benchmark you used.

Answer: 68°

Adjacent angles along a straight line add to 180°. Subtract 112 from 180. The explanation must identify the selected angle region and use 90°, 180°, or 360° as appropriate.

Scoring (3 points): 1 point for identifying the relevant property; 1 for a correct solution; 1 for reasoning.

Question 24 · construction · 4 points

Using a protractor, construct an angle measuring 145°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 145° angle with labeled rays

Check placement of the center and zero baseline; mark 145°, draw second ray, and label.

145°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 25 · classification · 2 points

Classify a 30° angle as acute, right, obtuse, or straight.

30°
Answer: acute

Compare 30° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 26 · classification · 2 points

Classify a 65° angle as acute, right, obtuse, or straight.

65°
Answer: acute

Compare 65° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 27 · reflex angle · 2 points

The smaller angle between two rays is 149°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 211°

Reflex angle = 360°−149°=211°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 28 · reflex angle · 2 points

The smaller angle between two rays is 84°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 276°

Reflex angle = 360°−84°=276°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 29 · classification · 2 points

Classify a 50° angle as acute, right, obtuse, or straight.

50°
Answer: acute

Compare 50° to 90° and 180°. A ray length does not affect the turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 30 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 100°

Align the protractor at the vertex and read from the baseline: 100°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 31 · reflex angle · 2 points

The smaller angle between two rays is 119°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 241°

Reflex angle = 360°−119°=241°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 32 · construction · 4 points

Using a protractor, construct an angle measuring 135°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 135° angle with labeled rays

Check placement of the center and zero baseline; mark 135°, draw second ray, and label.

135°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 33 · angle arithmetic · 2 points

An angle of 133° lies next to another angle on a straight line. Find the missing angle.

Answer: 47°

Adjacent angles along a straight line add to 180°. Subtract 133 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 34 · construction · 4 points

Using a protractor, construct an angle measuring 40°. Label its vertex and both rays.

Use the space to draw both rays
Answer: A correctly constructed 40° angle with labeled rays

Check placement of the center and zero baseline; mark 40°, draw second ray, and label.

40°

Scoring (4 points): 1 point for a correctly interpreted diagram or setup; 1 for a valid method; 1 for the result; 1 for clearly labeled construction/dimensions.

Question 35 · reflex angle · 2 points

The smaller angle between two rays is 70°. Find their reflex angle.

?°Reflex turn: use the outside region
Answer: 290°

Reflex angle = 360°−70°=290°. Mark the outside turn.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 36 · measurement · 2 points

Measure the smaller indicated angle between the two rays, in degrees.

?°
Answer: 140°

Align the protractor at the vertex and read from the baseline: 140°.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.

Question 37 · angle arithmetic · 2 points

An angle of 85° lies next to another angle on a straight line. Find the missing angle.

Answer: 95°

Adjacent angles along a straight line add to 180°. Subtract 85 from 180.

Scoring (2 points): 1 point for a sound method and 1 point for a correct, labeled answer.