a 7.5M Ladder is leaned up against a wall, what angle does the ladder make with the wall if the top of the ladder is 6.6m above the ground?

When the top is 6.6 meters above the ground, the cosine of an angle the ladder makes with the wall is given by:

cos(θ)=6.6/7.5=0.88

θ=arccos(0.88)=28.36°