Question

如下图,已知CD⊥AB于D,点E为BC上任意一点,EF⊥AB于F,且∠1=∠2=58,∠3=98,求∠ABC的度数.

Answer 1

∠A=108-∠3-(90-∠1)

=180-98-90+58

=50

∠B=90-∠2

=90-58

=32

∠ACB=180-∠A-∠B

=180-50-32

=98