This has been causing me some pain.

An 89.03 kg person is half way up a uniform ladder of length 3.453 m and mass 22.75 kg that is leaning against a wall. The angle between the ladder and the wall is θ. The coefficient of static friction between the ladder and the floor is 0.2561. Assume that the friction force between the ladder and the wall is zero. What is the maximum value of the angle θ between the ladder and the wall before the ladder starts slipping?