Question

If one angle of a triangle is equal to the sum of the other two angles which are equal, then the triangle is a/an _________ .

• A. Acute angled triangle
• B. Obtuse angled triangle
• C. Right angled triangle
• D. Equilateral triangle

Answer 1

The correct option is C

Right angled triangle

Let the two equal angles be x.

Then the third angle y = 2x

Also we know,
y + 2x = 180° (Sum of the angles of a triangle is 180°)

2x + 2x = 180°

4x = 180°

x = 45°

Hence the two equal angles are 45° each and the other angle is 90° which makes this triangle a right angled triangle.