Given isosceles triangle ABC with base BC If each base angle

Given isosceles triangle ABC with base BC. If each base angle I measures 75 degree and each leg is 40 inches long, find the area of this triangle. 400 squareroot 2| 400| 10| 400 squareroot 3| 800| None of these.

Solution

Equal sides are the legs = 40 inch

The vertex angle = 180 - 75 -75 = 30 deg

So, Area of trainagle = (1/2)*AB*AC*sin(angle between the 2 sides)

= (1/2)*40*40*sin30

= 1600/4 = 400

Option B