Question

如图，直线AB,CD相交于点O，OA平分∠EOC。（1）若∠EOC=70°，求∠BOD的度数（2）若∠EOC：∠EOD=2:3，

求∠BOD的度数

Answer 1

①∠BOD=0.5*∠EOC=35°
②∠BOD=∠AOC=0.5*∠EOC=180°*2/3=36°

Answer 2

(1)∠BOD=∠AOC=1/2∠EOC=35
(2)设∠EOC=X ∠EOD=3X/2 X+3X/2=180 X=72 ∠BOD=36

Answer 3

（1）解：∵OA平分∠EOC，∠EOC=70°
∴∠AOC=∠EOC×½=70°×½=35°
∵∠AOC与∠BOD互为顶角
∴∠BOD=∠AOC=35°

Answer 4

如图所示就可以了