Determining the support reactions of a frame

AI Thread Summary
To determine the support reactions at points A and B of the frame, the user initially separated the frame at the hinge and set up moment equations. They derived three equations from the forces and moments but faced a challenge with four unknowns. A suggestion was made to include the other part of the frame with support B, which would provide additional equations. It was confirmed that solving for Cx and Cy would lead to the remaining unknowns, emphasizing the importance of consistent sign conventions. Properly accounting for the direction of forces is crucial in completing the calculations.
hobbyenthusia
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Here is a link to the problem:
http://img62.imageshack.us/img62/374/frameow.jpg"
I am trying to find the support reactions at A and B.
I separated the frame at the hinge(call it C) into two parts and took the moment equation about point A.
This gave me: \SigmaMa = -60(25) - 62.5(12.5) + Cx(25) + Cy(25)
The forces in the y:\Sigma Fy = -62.5 + Cy + Ay
The forces in the x: \Sigma Fx =60 + Ax - Cx

From here I am unsure what to do as I have four unknowns and only three equations.
 
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:smile:Hello hobbyenthusia(st), welcome to these forums!:smile:

Try looking at the other part of the frame that includes the support at B. That should give you a total of 6 equations with a total of 6 unknowns.
 
I completely missed that. Thank you.
After taking the moments for each side is it as simple as solving Cx in terms of Cy or vice versa and finishing it up?
 
Yes, solve for Cx and Cy and the rest will follow. Please watch plus and minus signs! If Cx is assumed or found to act to the left on the left section, it must act to the right on the right section.
 
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