Question

一、如图一,已知：在三角形ABC中,延长BC至点E,BF,CF分别平分∠ABC,∠ACE,且BF与CF相交于F

Answer 1

因为∠A=180-∠ABC-∠ACB

∠F=180-∠ABC/2-(180-∠ACB)/2-∠ACB

=180-∠ABC/2-90+∠ACB/2-∠ACB

=90-∠ABC/2-∠ACB/2

所以∠F=1/2∠A