Statics - 3 forces acting at a point -- angle α maxima

[SFG]

Homework Statement

Please if anyone could help me with this question .

Two wires AC and BC are attached to the top of pole CD . The force exerted by the pole at C is vertical and the 2.5 kN force applied at C is horizontal and makes an angle α with the direction of the x-axis .

Find the angle α for which the tension in AC is a maximum and the corresponding tension in each cable .

as per pdf diagram

Homework Equations

Cos ^2 ɸx + Cos ^2 ɸy + Cos ^2 ɸz = 1

F = √Fx^2 + Fy^2 + Fz^2

Cos ɸz = Fz/F

The Attempt at a Solution

Formulate a quadratic then differentiate to get a maxima .

Sorry I cannot find the start point for this solution . Please help

 

[paisiello2]

Try summing forces in the x-direction.

 

[mfb]

Which force balances do you see that you can set up?

 

[SFG]

guys I am looking . seriously I am blanked without knowing another force or vector locations . regards SFG

 

[mfb]

The top of the pole is the only thing that can move, so it is useful to look at forces acting on that.
If you do not know a quantity, introduce a variable for it. That is something you will have to do frequently and everywhere.

 

[SFG]

ok thanks guys . i'll work on this overnight . regards