How Do You Solve for Unknown Forces in a Truss System Using the Point Method?

[petersun825]

Homework Statement

Below is a truss system, use the point method to solve for all forces within the trusses.

http://tinypic.com/view.php?pic=25i2dma&s=3

my question, If I take pin F then I have 4 trusses, 2 of them known(FE, FD) and 2 unknowns(GF, CF). exactly what should I do with truss GF and FC, they have forces in x and y axis.

Homework Equations

3. The atthis is what I've found so far
http://tinypic.com/view.php?pic=2q9ig05&s=3
F_DE=2.6 (T)
F_FE = 3 (C)

http://tinypic.com/view.php?pic=f52428&s=3
F_CD = 2.60 (T)
F_DF = 1 (T)tempt at a solution

 

[PhanthomJay]

At F, solve for the member forces under the known x component of force from FE, then solve for the member forces under the known y components of force from FE and FD, and then add the results together. Also, your forces in DE and FE are not right, you seem to have assumed a 30 degree angle, which it is not.

 

[petersun825]

oh ok thanks.