- #1

eurekameh

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So I'm looking for the reaction forces at the left end of the truss before I solve for the forces in the members of the truss in terms of F and theta. I summed forces in the x, y direction, took moments about point A,B, to get 4 equations in 4 unknowns (Ax, Ay, Bx, By). However, although Ax,Bx can be solved easily, I'm having trouble finding Ay,By because it appears as if my force and moment equations are not independent of one another. I've never had this problem before in my Statics class (this is for a numerical methods class), so I'm wondering if this problem is statically indeterminant.

Btw, each member is H long.

Here are my equations:

Force summation in x:

Ax + Bx + 2Fcostheta = 0

Force summation in y:

Ay + By + 2Fsintheta = 0

Moment summation at B:

AxH + 2FsinthetaH + FcosthetaH = 0

Moment summation at A:

-BxH + 2FsinthetaH + -FcosthetaH = 0

I solved the two moment equations for Ax and Bx. The force summation in the x direction confirms my Ax, Bx reaction forces. Thus, I still have two unknowns (Ay, By) in one equation (force summation in y). How do I solve for them? I've also tried summing moments at the right-hand corners, but they gave me equations which are also dependent.

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