Question

如图，D是△ABC的BC边上一点，∠B=∠BAD，∠ADC=80°，∠BAC=70°.求：（1）∠B的度数；（2）∠C的度数.

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Answer 1

1)
∠ADC=∠B+∠BAD=80°
又∠B=∠BAD
∠B=40°
2)
∠C=180°-∠B-∠BAC
=180°-40°-70°
=70°