besar CED= (pakai cara)

<AEC + <CED + <DEB = 180°
4x + 4 + 3x + 8 + 5x = 180°
4x + 5x + 3x + 4 + 8 = 180°
12x + 12 = 180°
12x = 180° - 12
12x = 168°
x = 168° : 12
x = 14

<CED = 3x + 8
= 3(14) + 8
= 42 + 8
= 50° (A)