Question

In an isosceles triangle, if the vertex angle is twice the sum of the equal base angles, then the angles of the triangle are

• A. 120^o, 30^o, 30^o
• B. 90^o, 45^o, 45^o
• C. 60^o, 60^o, 60^o
• D. 80^o, 50^o, 50^o

Answer 1

The correct option is A

120^o, 30^o, 30^o

Let the base angles be x and x.

Then, vertical angle = 4x.

Now, x + x + 4x = 180^o (angle sum property of a triangle)

x = 30^o

Hence, angles of the triangle are 120^o, 30^o, 30^o.