Given:
The base of the traingle is, b = 21 ft.
The height of the triangle is, h = 5 ft.
The area of the triangle can be calculated as,
[tex]A=\frac{1}{2}bh[/tex]
Substituting, we get,
[tex]A=\frac{1}{2}\times21ft\times5ft=52.5ft^2[/tex]
Thus, the area is 52.5 ft²
