Answer:
8.5 is the answer.
You use the formula a^2+b^2=c^2.
plug your numbers into the formula
a^2+7^2=11^2
Then you square the numbers so you'll end up with
a^2+49=121
Subtract 49 from both sides.
72.
Now, you take the square root of 72.
You'll end up with 8.485281374
Lastly, you round the number, which will give you 8.5