#17
so you would use the pythagorean's theorem
a^2+b^2=c^2
so we know that a and b are both equal since the shape is a square so let's call them x and c would equal 26
so the equation would look like
x^2+ x^2=26^2
2x^2=676
x^2=338
x= square root of 338 which is approximately 18.4
i hope this helps!
