1. The problem statement, all variables and given/known data http://i.imgur.com/fiUPD.png 2. Relevant equations Asin(Theta) Acos(Theta) Ax+Bx=Cx, Ay+By=Cy Cx^2+Cy^2=C^2 3. The attempt at a solution My problem is with the answer I got for part a). I used 3cos120 and got 2.44. Then put in 3sin120 and got 1.74. I added these to the Bx and By quantities and got 2.44=Cx and 4.74 for By. (Since B is on the origin I used (0 and 3 for Bx and By respectively). After squaring and finding the square root of C, I got 5.33. Which is close to the answer of 5.2 in the back of the book, but I just wanna make sure I'm doing everything corrct, but perhaps the number I got is a bit off due to some rounding up. THank you for your time. Edit: I also got 62.76 degrees for the arctan of Cy/Cx (4.74/2.44), which is still close to the 60 degrees the book says. Thank you once again for your help.