If ac is 50 feet, and ab is 40 feet, which is the length of bc?

Assuming that these are all sides of a right triangle, i would make sense if AB and BC were legs of a triangle, with the AC being the hypotenuse. Given these, we can use the pythagorean theorem to solve for the missing length. This is shown below:

AB^2 + BC^2 = AC^2

40^2 + BC^2 = 50^2

BC^2 = 50^2 - 40^2

BC^2 = 2500 - 1600

BC = sqrt (900)

BC = 30

Therefore, BC is 30 feet long.