Triangle DEF is similar to triangle ABC. Given that ∠C = 50°, what is the measure of ∠D ?

A. 40°
B. 90°
C. 10°
D. 50°
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The median am of triangle ∆abc is half the length of the side towards which it is drawn, bc . prove that triangle ∆abc is a right triangle, and find angle mac and abm