Question

如图,已知CF,BF分别是三角形ABC的外角∠DCB,∠CBE的角平分线,若∠A=60°,求∠F的

Answer 1

∵∠DCB=180°-∠ACB

∠CBE=180°-∠ABC

∵CE 和BE是角平分线

∴∠FCB+∠FBC=180°－1/2(∠ABC+∠ACB)

∵∠A=60°

∴∠ABC +∠ACB =120°

∴∠FCB+∠FBC=120°

∴∠F=60°