A ladder leaning against a vertical wall reaches a window 12 m above the ground and makes an angle of 60° with the ground. The distance of the foot of the ladder from the wall is:

The 12 m is the vertical leg, so tan60° = 12/d and d = 12/√3 = 4√3 ≈ 6.93 m. Multiplying by the tangent instead gives 12√3 ≈ 20.8 m, which would put the foot further from the wall than the window is high — impossible at a steep 60°. The ladder's own length is 12/sin60° = 8√3 ≈ 13.86 m, and 6 m would be right only if the 12 m were the ladder rather than the height.