Step-by-step explanation:
The area A of a triangle is given by
[tex]A = \frac{1}{2}bh[/tex]
where b is the length of the base and h is its height. Solving for h, we get
[tex]h = \dfrac{2A}{b} = \dfrac{2(72\:\text{m}^2)}{28\:\text{m}}[/tex]
[tex]\:\:\:\:= 5.14\:\text{m}[/tex]
