Answer :

Use Pythagorium Thorem :
Hypotheuse
c²=a²+b²
c²= √9²+11²
c=√202
c=14.21
If it's a right triangle, then you would use the Pythagorean Theorem.
9^2 * 11^2 = c^2
202=c^2
The hypotenuse would equal the square root of 202 which is about 14.213