An isosceles trapezoid is one that has 2 bases of different lengths and the other 2 sides having the same length as each other (definition of isosceles trapezoid). So if the perimeter is 79.53, the the formula is 79.53=x+x+25.62+33.51 and 79.53=2x+59.13. Solve that for x to get that x=10.2. That's your answer! Each leg is 10.2 meters long.