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Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

Given the parallelogram shown above, what is the value of x°?

A.48°
B.72°
C.108°
D.132°

答案和解析

答案：A

解析：

Choice A is correct. The diagonal through the figure forms a transversal of the upper and lower sides. Since this is a parallelogram, the alternate interior angles are congruent.

Below, the alternate interior angle of the 72° angle is labeled.
Now use the interior angle sum property of triangles to solve for the measurement x°. Recall that the interior angles of a triangle have a sum of 180°.
Likewise, adjacent angles of a parallelogram are supplementary. Thus, 72+x+60=180.