What is the vertex angle of an isosceles triangle whose equal side are 15 meters long if the area is 112.5 square meters?

Solution:

We assume the angle is X.

The area of the triangle = 0.5*a*b*sinX, a and b are two sides of the angle X.

Here

0.5*15*15*sinX = 112.5

sinX = 1

X = 90 degree

So  the vertex angle is 90 degree