Question

In a ΔАВС, ∠C = 3 ∠B = 2(∠A + ∠B), then ∠B = ?

Options

• 20°

• 40°

• 60°

• 80°

Answer 1

40°

Explanation:

Let C = 3B = 2(A + B) = x°.

Then, C = x°, B = `(x/3)^circ` and (A + B) = `(x/2)^circ`.

(A + B) + C = 180°

⇒ `x/2 + x = 180^circ`

⇒ 3x = 360°

⇒ x = 120°

∴ `∠B = (120/3)^circ = 40^circ`.