Since it is an isosceles triangle, both legs are congruent. So you could use the a^2+b^2=c^2
but since two legs are equal it would be a^2+a^2=c^2 2a^2=144^2 2a^2=20,736 a^2=20736 / 2 a^2=10,368 square root of a^2=square root of 10,368 a=square root of 10,368 or 101.82