Question

Find the missing side length

Answer 1

We will use the  Pythagoras theorem which will say
 
17^2 -15^2 = the side length
 289 - 225  =  64
then you square root the answer
                  =  √64
                  =    8
side length  =  8              

Answer 2

17^2 - 15^2
= 289 - 225
= 64

missing side = √64 = 8

answer
A. 8