Question

几何证明题，要详细过程！

Answer 1

∵∠BOC+∠BOD=180
∠BOC=∠BOD-30
∴∠BOC=75
∠BOD=105
∵∠BOC=∠AOD
∴∠AOD=75
∵OE平分∠AOD
∴∠DOE=∠AOD/2
∴∠DOE=37.5
∵∠DOE+∠COE=180
∴∠COE=142.5

Answer 2

因为cd为直线所以∠cod=180°所以∠cob+∠cod=180°因为∠cob=∠cod-30°可知∠cob=75°∠bod=105°因为ab为直线所以∠aoc与∠bod相等=105°∠boc=∠aod=75°对顶角相等∠aoe等于1/2∠aod等于37.5°所以∠coe等于105°加37.5°=142.5°