Let x be the length of either leg (the legs are congruent, since the triangle is isosceles).
Then the area of this right-angled triangle is = 5000 m^2, which implies
= 10000 m^2, i.e. x = 100 m.
Then the hypotenuse is and the perimeter is m.
Solved.
Notice that "josgarithmetic" mistakenly uses the term "diagonal", which is not applicable in this case.