jawablah no 10 berikut

ctt < = sudut

jawab

<ABC + <CBD = 180° (sudut berpelurus)
<ABC + 140° = 180°
<ABC = 180° - 140°
<ABC = 40°

<ABC + <BCA + <BAC = 180°
40° + 2y + 10° + y + 10° = 180°
3y + 60° = 180°
3y = 180° - 60°
3y = 120°
y = 120°/ 3
y = 40°

jadi.
<BAC = y + 10°
<BAC = 40° + 10°
<BAC = 50°

somoga membantu...