Section C Section C Checkpoint

Problem 1

Angle S and the angle that is 138∘138^\circ make a straight angle. What are the measurements of Angles S and T? Explain or show your reasoning.

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Solution
  • Angle S is 42∘42 ^\circ. Sample response: Angle S and the 138∘138 ^\circ angle make a straight angle, and 180−138=42180 - 138 = 42.
  • Angle T is 160∘160 ^\circ. Sample response: 180−20=160180 - 20 = 160
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Sample Response
  • Angle S is 42∘42 ^\circ. Sample response: Angle S and the 138∘138 ^\circ angle make a straight angle, and 180−138=42180 - 138 = 42.
  • Angle T is 160∘160 ^\circ. Sample response: 180−20=160180 - 20 = 160

Problem 2

  1. Decide if each angle in the triangle is acute, right, or obtuse.

    triangle. two acute angles. one obtuse angle.

  2. Draw a triangle with one right angle. Label the right angle B.
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Solution

Sample responses:

a.
triangle

b.

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Sample Response

Sample responses:

a.
triangle

b.

Problem 3

What are the measurements of Angles A and B if all of the angles add up to 180 degrees? Explain or show your reasoning.

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Solution
  • Angle A is 90∘90^\circ because the rays that create the angle are perpendicular.
  • Angle B is 15∘15 ^\circ because six of them make a 90∘90^\circ angle (180−90=90180 - 90 = 90), so each of them is 90÷690 \div 6 or 15 degrees. 
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Sample Response
  • Angle A is 90∘90^\circ because the rays that create the angle are perpendicular.
  • Angle B is 15∘15 ^\circ because six of them make a 90∘90^\circ angle (180−90=90180 - 90 = 90), so each of them is 90÷690 \div 6 or 15 degrees.