For a cyclic quadrilateral
The opposite angles are supplementary (meaning they sum up to 180 °)
I.e (x +20) ° + 3x ° =180 °
20 + 4x = 180
4x=180 - 20
4x = 160
Divide through by 4
x = 40 °
Angle at point A
(2x + 38) = (2(40) + 38) = 118 °
Angle at point B
3x = 3(40) = 120 °
Angle at point D
x + 20 = 40 + 20 = 60 °
Angle at point C
The total angle in a quadrilateral is 360 °
I.e 118 + 120 + 298 +
