Hello billionj

Welcome to Math Help Forum!Imagine that you cut the isosceles triangle straight down the middle from vertex to base, to form two identical right-angled triangles. Then in one of these triangles, the hypotenuse is feet long, and the angle adjacent to the base is . So the length of the base is:

This is just one-half of the base of the original triangle. So its length is:

feet (to the nearest foot)Grandad