http://img366.imageshack.us/img366/5171/phwq5.jpg [Broken] Hello there. In lab, we measured vectors. I'm having a little concern on how to get X and Y. If I follow the books method, R_calc comes out too small compare to measure R. (Big % error). X: 15.5+12.4cos37 = 25.4 Y: 0+9.3sin37 = 5.4 R: square root of (25.4^2+5.4^2) = 26cm If I do it my way, R is a lot closer to measure. X: 15.3+12.4= 27.9cm Y: 0 + 9.3 = 9.3 cm R: square root of (27.9^2+9.3^2) = 29.4 cm The measurements (x1/2; y1/2; R m) are pretty accurate. What am I doing wrong? Thanks for any help.