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furv

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## Homework Statement

"A force F of magnitude 90 kN is applied at point C at an angle of 45°. The pin-joint B may be assumed to be resting on frictionless rollers. Determine the reaction forces at A and B"

Image of the diagram here: http://i.imgur.com/jUL0rJe.jpg?1

## Homework Equations

two force principle

three force principle

sum of moments = 0

sum of X components = 0

sum of Y components = 0

## The Attempt at a Solution

First I started to try and fill in the free body diagram and considered AB. B is on frictionless rollers, so to stay in equilibrium I thought the reaction force must only be able to act vertically. At A I don't know the direction of the reaction force so I just drew in arrows for the X and Y components, At D I again had it perpendicular to AB vertically up ( not sure if this was correct ). I then resolved horizontally and vertically; Y: Ya+Rd+Rb=0 X: Xa = 0. Then I took moments about A : Rd(4.5)+Rb(9)=0. There's too many unknowns to solve so i know i have to resolve somewhere else but i'm not sure about the directions of the forces acting on C to try and resolve AC or CB.. Maybe i'm going about it completely wrong, as already it feels wrong having the X component of A being 0 if I look at the rest of the diagram.

Any help will be greatly appreaciated