Question

The angles of a triangle are : 2(x + 6)°, 3(x - 1)° and 6(x + 1)°. Find x, and show that the triangle is isosceles.

Answer 1

We know that the sum of all angles of a triangle are 180°
Thus, 2(x + 6)° + 3(x - 1)° + 6(x + 1)° = 180°
⇒ Collecting like terms, we get:
(2x + 3x + 6x)° + (12 + 6 - 3)° = 180°
⇒ 11x° = 180° - 15° = 165°
⇒ x = 15°.