Checking truss member forces and weight calculation

[pooface]

Homework Statement

http://img150.imageshack.us/img150/1196/cci0710200700003dy8.jpg
The problem and diagram is given on the sheet.

Homework Equations

sigma Fx=0
sigma Fy=0

The Attempt at a Solution

Starting freebody from point B
T=tension, C=compression

TBC = cos36.86deg = 3250N cos22.62deg
TBC = 81.39N

CBE = 81.39sin36.86deg + 3250sin22.62deg
CBE = 1.3KN

Now using Freebody at point C

TDCcos45deg = 81.39cos36.86deg
TDC=92.09N

M=92.09sin45deg + 81.39sin36.86deg
M=113.94N [FINAL ANSWER]

am i doing this correctly? did i make a mistake anywhere? I have a test tomorrow i need to know if i am missing some fundamental knowledge.

thank you for taking the time to help me.

 

[learningphysics]

"TBC = cos36.86deg = 3250N cos22.62deg
TBC = 81.39N"

what happened here? TBCcos(36.86) = 3250cos(22.62) doesn't give TBC =81.39.

other than this your work looks right to me.

 

[pooface]

shoot! yes you are correct. I don't know how I miscalculated. It is a risk using shift-ANS function on my calculator, sharp el520. if you press = it will overwrite the memory for ANS and you can't go back.

thank you. mistakes like this will ruin me on the test...if TBC is wrong then TDC will be wrong and so on.

thanks again learningphysics!

 

[learningphysics]

shoot! yes you are correct. I don't know how I miscalculated. It is a risk using shift-ANS function on my calculator, sharp el520. if you press = it will overwrite the memory for ANS and you can't go back.

thank you. mistakes like this will ruin me on the test...if TBC is wrong then TDC will be wrong and so on.

thanks again learningphysics!

Yeah, hopefully the professor will check your work and see what you were doing and only grade you down for that 1 mistake... this is the only mistake I saw in your work... I'd personally give you at least a 9/10... you're welcome. glad to help.