Take into account that the formula for the area of a triangle is:
A = b·h/2
where b is the base, h is the height h = 7.2 cm and A is the area A = 28.8 cm²
Solve for b in the previous formula, and replace the values of A and h, as follow:
b = 2·A/h
b = 2(28.8 cm²)/(7.2 cm)
b = 8 cm
Hence, the length of the base of the triangle is 8 cm
