Well, we know that the legs of this triangle are equal, and we know
that the area of any triangle is (1/2)(base)(height) .
Since this is a right triangle, we can set it down on one leg, and then
the other leg will be the height. Then ...
Area = (1/2) (base) (height)
= (1/2) (leg) (leg)
65 cm² = (1/2) (leg)²
Multiply each side by 2 : 130 cm² = (leg)²
Take the square root of each side: leg = √130 cm² = 11.402 cm
rounded to the nearest tenth: 11.4 cm