How Do I Minimize Cable Tension in Engineering Mechanics?

[CivilSigma]

Homework Statement

For the structure and loading of Prob. P2.46 a) determine the value of $$\alpha$$ for which the tension in cable BC is as small as possible b) the corresponding value of the tension

(Please see attachement of diagram).

Homework Equations

Finding the components of forces, or constructing a triangle of forces - I know how to do b) but not a)

The Attempt at a Solution

I remember my professor mentioning that in order for a force to be as small as possible, we need to have the triangle of forces in a right angle triangle. I do not know how to setup the problem, if someone can help me with that I would appreciate it.

Thanks!

 

[SteamKing]

Why don't you start by setting up a free body diagram of the boom AC?