not very sure how to solve this

Hi Marisa;

a

^{2}+b^{2}=c^{2}a

^{2}+b^{2}=9^{2}Because this is a square, a=b...

2a

^{2}=9^{2}2a

^{2}=81Let's divide both sides by 2...

(2a

^{2})/2=81/2a

^{2}=40.5square-root both sides...

√a

^{2}=√40.5a=6.36