Question:
The angles of a quadrilateral are in the ratio 3 : 4 : 5 : 6. The smallest of these angles is
(a) 45°
(b) 60°
(c) 36°
(d) 48°
Solution:
(b) 60°
Explanation:
Let ∠A = 3x, ∠B = 4x, ∠C = 5x and ∠D = 6x.
Since the sum of the angles of a quadrilateral is 360o, we have:
3x + 4x + 5x + 6x = 360o
⇒ 18x = 360o
⇒ x = 20o
∴ ∠A = 60o, ∠B = 80o, ∠C = 100o and ∠D = 120o
Hence, the smallest angle is 60