perhatikan gambar berikut jika sudut AOE siku-siku, besar COB =....

(2x-2)+(3x+7) = 90
5x+5 = 90
5x = 90-5
5x = 85
x = 85/5
x = 17

AOC = DOB
maka COB = 180-AOC
COB = 180-(3.17+7)
COB = 180-(51+7)
COB = 180-58
COB = 122°

Bab Garis dan Sudut
Matematika SMP Kelas VII

2x - 2 + 3x + 7 = 90°
5x = 90° - 5
x = 85° : 5
x = 17°

∠AOB = ∠AOC
∠COB = 180° - ∠AOC
∠COB = 180° - (3x + 7°)
∠COB = 180° - (3 . 17° + 7°)
∠COB = 180° - 58°
∠COB = 122°