Formula used:
Area of equilateral triangle
Given that the three triangles are equilateral and therefore the area of the three triangles will also be same.
Now area of one equilateral triangle with side
Therefore the area of triangle having side
So the area of all three triangles
the area of trapezoid
(Answer)
Refrence:
Equilateral Triangle
http://en.wikipedia.org/wiki/Equilateral_triangle
