jawab ya ntr gua kasih poin buanyaak

ABCD merupakan segiempat tali busur sehingga berlaku [tex]\angle{BAD} + \angle{BCD} =180^{\circ}[/tex].
[tex](x + 20) + 3x = 180 \\ 4x = 180 - 20 \\ 4x = 160 \\ x = \frac{160}{4} = 40[/tex]
Subtitusikan.
[tex]\angle{BAD} = x + 20^{\circ} = 40^{\circ} + 20^{\circ} = 60^{\circ} \\ \angle{BCD} = 3x = 3 \cdot 40^{\circ} = 120^{\circ} [/tex]
ROM A
[tex]\angle{BOD} minor =2 \angle{BAD} = 2 \cdot 60^{\circ} = 120^{\circ} [/tex]
ROM B
Kita tahu bahwa [tex]\angle{BOD} minor + \angle{BOD} mayor =360^{\circ} [/tex].
[tex]120^{\circ} + \angle{BOD} mayor = 360^{\circ} \\ \angle{BOD} mayor = 240^{\circ} [/tex]