posted by Alex .
At a certain time of day, a tree that is Xft tall cast a shadow that is X-35 meters long if the distance from the top of the tree to the end of the shadow is X+5 meters, what is the height, X, of the tree?
It is an odd problem, but you assuming the tree is vertical to the surface...
x^2+(x+5)^2=(x-35)^2 from the right triangle. Solve for x.