The Official SAT Question of the Day™

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



In the figure above, four lines intersect as shown. If a = 30 and line l is parallel to line m, how many of the seven angles marked with arrows must have measure 30°?

A One
B Three
C Four
D Five
E Seven

Answer is B

Here's Why:

The vertical angle to that marked 30° also has measure 30°, because the measures of vertical angles are equal. Since line is parallel to line m, the corresponding angles to the two angles at the lower left also have measure 30°. Thus, all three of the marked angles at the left of the figure have measure 30°.

Although line is parallel to line m, the other two lines in the figure need not be parallel to each other. They look as if they might be parallel, but you cannot be sure just by looking. Thus, none of the four marked angles at the right of the figure must have measure 30°. Therefore, exactly three of the angles marked with arrows must have measure 30°.


Difficulty: Medium
Question Type: Standard Multiple Choice