Find Force exerted

(see attachments)  
FYI: In this posting I will write A (sub x) as Ax.  I will Write Sigma (or sum) as {E}

Find the force exerted by pin A on the structure.  

I know that i first make the free body diagram.  

1. Try the entire frame: IN second attachment, image on left.
     Problem...this is 4 unknowns, but we're only allowed 3 unknowns in a 2-D   situation.  The 4 are : Ax, Ay, Bx, By.  The three eqns. available are  {E}Fx=0   ;    {E}Fy=0    ;     {E}M=0

     So, i decided that this won't work.

2. Try FBD of AD: the second attachment, image on right
        Again there are 4 unknowns, this time they are Ax, Ay, Cx, Cy...This won't work.  

However I think that I may be able to combine the two systems of equations.  

->  Ax, Ay, Bx, By, Cx, Cy

Now what?  I think I may have to solve for Ax and Ay?  How do I finish this?  Thanks!

Attached file(s):

StressP2.jpg  View File

FBDA.jpg  View File