Perhatikan gambar berikut! Jika ∠ DOB siku-siku, maka besar sudut ∠ COB = ....

180° = (3x - 5)° + (2x + 10)°
180° = 3x° - 5° + 2x° + 10°
180° = 5x° + 5°
175° = 5x°
35° = x

(2x + 10)° = ([2 × 35] + 10)° = 80°

90° - 80° = 10°

Jadi, besar sudut <COB adalah 10°.



semoga membantu

<DOA + <DOC = 180°
3x - 5 + 2x + 10 = 180
5x + 5 = 180
5x = 180 - 5
5x = 175
x = 175/5
x = 35

<DOC = 2x + 10
<DOC = 2 x 35 + 10
<DOC = 80°

<COB = 90° - 80°
<COB = 10°

*semoga membantu. sukses selalu ^_^