Answer:
60
Step-by-step explanation:
We can use the pythagorean theorem to find the leg.
10^2+x=13^2
x=12
We now find the area given the height of the triangle.
10 X 12=120
120/2=60
1,008 square yards
21 yards long X 48 feet wide = 1,008 square yards
hope it helps!