You've just planted a young tree, which you want to support so that it doesn't blow over in the wind. if you attach a 6-foot support rope 4 feet up on the tree, approximately how far from the bottom of the tree is the rope attached to the ground?
10 feet
2 feet
4 feet

The 6 foot rope forms a hypotenuse of a triangle with one side of 4 foot.  So by the Pythagorean Theorem we have:

6^2=4^2+x^2, where x is the distance from the tree that the rope is attached to the ground.

36=16+x^2

x^2=20

x=√20 ft

x≈4.47 which they rounded to nearest whole foot.

x≈4 ft.