Answer:
<h2>This triangle is a right triangle:</h2><h2>36² + 15² = 39².</h2>
Step-by-step explanation:
If a ≤ b <c is the length of the sides of a right triangle, then:

We have

Check the equality:



It's a right triangle.
A = 81 square in.
s = sqrt(A)
s = sqrt(81)
s = 9 in.
The answer is c. 
a.
(2.2≠5.11) (2.2 is not equal to 5.11)
b.
or 0.625 (0.625≠5.11) (0.625 is not equal to 5.11)
c.
(5.11=5.11) (5.11 is equal to 5.11)
Therefore c is the answer