Angles of Triangles Quick Check
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Question
Use the image to answer the question.
An illustration shows a right triangle. The right angle is at the left; the top angle is labeled a; and the angle on the right is labeled b. A line extending outward from angle a forms an exterior angle of 142 degrees.
Use the properties of exterior angles of triangles to find angle b.
(1 point)
A. 92°
B. 38°
C. 52°
D. 232°
The sum of the measures of the interior angles of a triangle is always 180 degrees.
Since the exterior angle at angle a is 142 degrees and the angle a itself is 90 degrees (as it is a right angle), we can subtract 90 degrees from 142 degrees to find the measure of angle b.
142° - 90° = 52°
Therefore, the answer is C. 52°.