Question

a triangle with side lengths 17, 10, 21 and height 8 (with a right angle symbol indicating the height is perpendicular to the base of length 21).

Explanation:

Step1: Recall triangle area formula

The area of a triangle is given by $\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$

Step2: Substitute given values

Here, base $=21'$, height $=8'$. Substitute into the formula:
$\text{Area} = \frac{1}{2} \times 21 \times 8$

Step3: Calculate the result

First compute $21 \times 8 = 168$, then $\frac{1}{2} \times 168 = 84$

Answer:

$84$ square feet