Angle of elevation problem... it's super simple, but the algebra I need help with ^_^

A ladder leaning against a building makes an angle of 78 degrees with the ground. THe foot of the ladder is 5 feet from the building. How long is the ladder?

Yadda yadda. Okay, a picture came with it, but I already figured out the problem and here is it:

cos(78) = 5/x

.......... = ...???

How do I get x by itself? Could someone please work the problem for me, and then I'll know how to do the rest. Isn't it annoying when you forget the little things? Thanks!