The area of any triangle is (1/2) x (length of the base) x (height) .
In this problem, we know the triangle's height,
but what is the length of the base ?
The base is the side that the triangle is sitting on. This particular triangle
is an equilateral one, and its perimeter is 60m. So each side must be 20m.
No matter which side the triangle is sitting on, the length of the base is 20m.
Area = (1/2) x (base) x (height)
Area = (1/2) x (20m) x (17.3m) = 173 m²