You would be looking to find the hypotenuse, being that both of the options are more than the values of the sides you gave
The equation is a^2+b^2=c^2
11^2+9^2=c^2
121+81=c^2
202=c^2
Now you need to find the square root of 202
So the exact answer would be √202
An approximate answer to the nearest hundredth would be 14.21