Question: how to find the magnitude of a vector given the x and y components?
Answer: Apply the equation. to find the magnitude, which is 8.6. Apply the equation theta = tan–1(y/x) to find the angle: tan–1(–7.0/–5.0) = 54 degrees. However, note that the angle must really be between 180 degrees and 270 degrees because both vector components are negative.