Answer
$147~ft^2\ , \ 56.0\ ft$
Work Step by Step
If we divide the triangle into two parts, we have two right triangles. Recall the Pythagorean theorem:
$$c^2=a^2+b^2.$$
We can use this to calculate the height of the triangle by making one of the legs equal to $16\div 2=8$:
$h^2+8^2=20^2$
$h=\sqrt{20^2-8^2}=18.33$.
Now that we have the height, we calculate the area:
$$
Area= \frac{1}{2} base \times height=\frac{1}{2}\times16\times 18.33=146.64\ ft^2\approx 147~ft^2
.$$
The perimeter of the triangle is the sum of the lengths of the sides. Thus, we have
$$perimeter= 16+20+20=56.0\ ft
.$$
