In an isosceles triangle, the vertex angle is four times the sum of the base angles. The measure of the square root of the vertex angle is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 12°.
Let the base angles of the given isosceles triangle be x cm each.
⇒ Vertex angle = 4(x + x) = 8x
Now, Sum of all angles of a triangle = 180°
⇒ 2x + 8x = 180°
⇒ 10x = 180°
⇒ x = 18°
Vertex angle = 8 × 18° = 144°
Now, Square root of vertex angle = = 12°