Question 186543
A triangle with sides in the ratio 3:4:5 is always a right triangle.
Is the side AC the short side? If so, then this is a 3:4:5 ratio with AC as 12.

perimeter = 20+16+12= 48 yards
area = (1/2)Base*Height = (1/2)12*16 = 96 sq yards

If this triangle is obtuse, let me know and we can work that one too