The angles of a quadrilateral are in the ratio 3 : 5 : 9 : 13.
Let ∠A+ ∠B : ∠C : ∠D = 3 : 5 : 9 : 13.
Sum of ratio = 3x + 5x + 9x + 13x = 30x
Sum of 4 angles of quadrilateral is 360°
∴ ∠A + ∠B + ∠C + ∠D = 360°
3x + 5x + 9x + 13x = 360
30x = 360 ∴ x = = 12°
∠A = 3x = 3 × 12 = 36°
∠B = 5x = 5 × 12 = 60°
∠C = 9x = 9 × 12 = 108°
∠D = 13x = 13 × 12 = 156°
