What Is the Magnitude of Vector A?

[FriskeCrisp]

Vector A, which is directed along an x axis, is to be added to vector B, which has a magnitude of 9.0 m. The sum is a third vector that is directed along the y axis, with a magnitude that is 6 times that of A. What is the magnitude of A? (Enter your answer to 4 significant figures.)

So I know that vector B is 9 m. With the given information, I made the assumption that vector A is Vector A + 9. And finally, the third vector, the sum, would be 6(vector A). Am I on the right train of thought with the problem? To solve for the missing variables, can I use a + b = c?

 

[nickjer]

Vectors have both magnitude and direction. You can't just add the magnitudes and ignore the directions. You will have to break up the vectors into x and y-components and add them. I suggest possibly drawing a picture.