Question

Don't know how to do this

Answer 1

I'm afraid your equation is not correctly set up.  You need to identify the longest side of this right triangle; it is x.  This is the "hypotenuse."  Next, identify the lengths of the legs:  they are sqrt(13) and 2sqrt(2).

Here's a refresher on the Pythagorean Theorem:

(hypotenuse)^2 = (leg 1)^2 + (leg 2)^2

Applying this Theorem here,  [x]^2 = [2sqrt(2)]^2 + [sqrt(13)\^2

Solve this for x^2, and then take the positive root (only) of your result.