Question

在三角形ABC中,角A等于60°BD平分角ABC,CD平分角ACB,求角BDC

Answer 1

由∠A =60°,∠ABC+∠ACB =120°

由BD.CD分别平分∠ABC和∠ACB得∠DBC+∠DCB =1/2*∠ABC+1/2*∠ACB=1/2*(∠ABC+∠ACB )=60°

所以∠BDC=180°-(∠DBC+∠DCB)=180°-60°=120°