A12-foot ladder rests against a brick wall at angle of 60°. which expression gives the value of x, the height on the brick wall where the ladder rests?

Using Pythagorean's Theorem we know that a^2 + b^2 = c^2

C is the length of the ladder, and we are given one of the sides, let's call that side b

we have a^2 + b^2 = c^2, and a^2 = c^2 - b^2, so a = √ c^2 - b^2

a = √12^2-3^2 = √ 144-9 = √ 135 = 11.61895 

so the top of the ladder is 11.6 feet above the ground

here u go hope this helps

entering that problem on the tube might get you an answer