at needs to determine the height of a tree before cutting it down to be sure that it will not fall on a nearby fence. The angle
of elevation of the tree from one position on a flat path from the tree is Upper H equals 60 degrees commaH=60°, and from a second position Upper L equals 20 feetL=20 feet farther along this path it is Upper B equals 40 degrees .B=40°. What is the height of the tree?