How do you find the area of something if you are given three different numbers?

First notice that we are finding the area of the trapezoid.
The area of a trapezoid is:
, 
where h is the height, b₁ and b₂ being the bases of the trapezoid. 
But before we find the area we have to find the side length of the third side in the triangle. To find this, we need to use the Pythagorean Theorem. 


When we solve this equation, we obtain 1.4387, which I will round to 1.4. 
Now, we use the area formula. The side length of the bottom base is 1.4 + 7 = 8.4. 
Plugging into the formula we get: