Question

在△ABC中,D,E分别是边AB,AC,上的点,且DE‖BC若∠ADE=55°∠C=60°则∠A的度数为

A.45°
B.65°
C.50°
D.40°

Answer 1

DE‖BC且∠ADE=55°
所以∠ABC=55°
又因为∠C=60°
根据三角形内角和180°知
∠A=65°
选B

Answer 2

DE//BC
∠ADE=∠B=55°
∠C=60°
∠A=180°-∠C-∠B
=65°