For this question, we use the Pythagorean theorem.

We know the lengths of the legs, a and b.


Now, let's solve for the hypotenuse, c.


Take the positive square root.

Hope this helps! :)
The base's length is 8 and it's width is 7, so it's perimeter will be

. To find the lateral area you shoul multiply this with it's height. So,

(h is height).