To find the area of a triangle, you do (base × height)/2.
In this case, the base would be 16, and the height would be 8 as it is the radius because 16 would be the diameter and the radius is half of the diameter.
This means you can do (16 × 8)/2 = 128/2 = 64.
So the area of the triangle is 64 ft².
I hope this helps!