Determine the Forces in the Specified Members.

[Northbysouth]

Homework Statement

Determine the forces in members BC, CF, and EF of the loaded truss. Forces are positive if in tension, negative if in compression.

I have included an image

Homework Equations

ƩM = 0
ƩF_y = 0
ƩF_x = 0

The Attempt at a Solution

I'm a little stuck on this one.

I tried using method of sections, whereby I drew a line through the middle of lines BC, CF and EF and then focused on everything to the right of that line. What this gave me is a system with two L forces, one at E and another at D as well as the forces of the members BC, EF and CD.

From here I tried to take the moment about point C,

ƩM_C = 0

0 = -L(d) + EFcos(17)

however I ran into difficulty because I couldn't figure out what the distance of CE is.

Help would be appreciated

 

[PhanthomJay]

Homework Statement

Determine the forces in members BC, CF, and EF of the loaded truss. Forces are positive if in tension, negative if in compression.

I have included an image

Homework Equations

ƩM = 0
ƩF_y = 0
ƩF_x = 0

The Attempt at a Solution

I'm a little stuck on this one.

I tried using method of sections, whereby I drew a line through the middle of lines BC, CF and EF and then focused on everything to the right of that line. What this gave me is a system with two L forces, one at E and another at D as well as the forces of the members BC, EF and CD.

From here I tried to take the moment about point C,

ƩM_C = 0

0 = -L(d) + EFcos(17)(length of CE)

however I ran into difficulty because I couldn't figure out what the distance of CE is.

Help would be appreciated

It's just a bit of trig and geometry to find the distance CE. The length 'd' is known and a couple of the angles...find the vertical legs of triangles with side d and angle theta...draw a sketch...otherwise, your equation is good when you add your omission noted in red