Use trigonometry. The ladder and the building form a right triangle with the ground. You are given the length of the hypotenuse and the base angle. You use sine since we are trying to figure out the opposite side from the angle and we have the hypotenuse length. Sin = opposite/hypotenuse. So in this case, sin 60°= x/10. We solve for x by multiplying both sides by 10. Now x= sin 60° (10) = (0.8660)(10) = 8.7 m.
