posted by Phil .
If vector B is added to vector C = 6.7 + 6.9, the result is a vector in the positive direction of the y axis, with a magnitude equal to that of vector C. What is the magnitude of vector B?
Magnitude of C: sqrt(6.7^2+6.9^2). figure that out.
so what is added?
so A must be -6.7i + (magnitude-6.9)j