1.有2种情况
① ∵∠AOB=30°
∠BOC=15°
∴∠AOC=∠AOB-∠BOC=15°
② ∵∠AOB=30°
∠BOC=15°
∴∠AOC=∠AOB+∠BOC=45°
2.90°-70°37′43〃=19°22′ 17〃
3.135°/180°=3/4
4.设这个角的度数为x.
(90-x)÷(180-x)=3/7
540-3x=630-7x
4x=90
x=22.5
1.有2种情况
① ∵∠AOB=30°
∠BOC=15°
∴∠AOC=∠AOB-∠BOC=15°
② ∵∠AOB=30°
∠BOC=15°
∴∠AOC=∠AOB+∠BOC=45°
2.90°-70°37′43〃=19°22′ 17〃
3.135°/180°=3/4
4.设这个角的度数为x.
(90-x)÷(180-x)=3/7
540-3x=630-7x
4x=90
x=22.5