Question 39 Answer and Explanation _ACT June 2011 Form 69F Math Section

39. In ΔOBC shown in the standard (x, y) coordinate plane below, M is the midpoint of OR, N is the midpoint of BC, and Q is the midpoint of OC. Which of the following statements is always true?

A. The slope of MN is equal to the slope of OC.

B. The product of the slope of MN and the slope of OC is -1.

C. The product of the slope of MN and the slope of OB is -1.

D. The product of the slope of MN and the slope of BC is 1.

E. MN $\cong$ OC

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

M and Q are the midpoints of OB and OC respectively, so MQ is parallel to BC, so the slope of MQ is always equal to the slope of BC. Choose A.