Find the area of triangle OBD. It is a triangle inscribed in a rectangle on a graph. E(0,7) D(8,7) C(12,7) B(12,3) A(12,0) O(0,0)

Question

I dont know how to find the area of the triangle inside because all of the formulas i am using i get a radical 

Answer 1

A solution may be a radical - they are numbers too!

1) determine area of rectangle AOEC

2) determine area of triangle OAD

3) determine area of triangle DCB

4) determine area of triangle BAO

5) subtract 2, 3, and 4 from 1, that is the area of ODB