Working out the coeffient of friction?

[mm874]

Homework Statement

A ladder of weight 250 N and of length 6.0 m....?
A ladder of weight 250 N and of length 6.0 m rests with its lower end on a horizontal rough concrete surface and its upper end against a smooth wall. If the ladder just starts to slip when the angle between it and the concrete is 550, calculate the coefficient of static friction μ.

Homework Equations

The Attempt at a Solution

Unfortunately I have no idea where to begin. So any help would be much appreciated.

 

[kuruman]

Begin by drawing a free body diagram (FBD) of the ladder.

 

[mm874]

Sorry, I had already done that and am still struggling! This has croppped up on a number of past exam papers but we haven't been through it in class.

 

[kuruman]

If you've already done it, show what you did and where you got stuck. We will help you get unstuck and stop struggling.