To calculate the area of the triangle you have to multiply its base by its height and divide the result by 2, following the formula
[tex]A=\frac{bh}{2}[/tex]Considering the given right triangle, the base and the height of the triangle are its legs:
The area can be calculated as:
[tex]\begin{gathered} A=\frac{bh}{2} \\ A=\frac{7\cdot24}{2} \\ A=\frac{168}{2} \\ A=84ft^2 \end{gathered}[/tex]The area of the triangle is 84ft²