Question

解题方法详解

Answer 1

在角形内角和=180.

∠A+∠B+∠C=180°

∠CBF=90°-1/2∠B

∠BCF=90°-1/2∠C

∠CFB=180°-(∠CBF+∠BCF)= 1/2∠B+1/2∠C

∠A+∠B+∠C=180°∠B+∠C=180°-∠A

∠F=∠B/2+∠C/2=(180°-∠A)/2=90-∠A/2