일반물리학 1 — Vectors: Problem 24

Vector \(\vec{A}\), which is directed along an x axis, is to be added to vector \(\vec{B}\), which has a magnitude of 6.0 m. The sum is a third vector that is directed along the y axis, with a magnitude that is 3.0 times that of \(\vec{A}\). What is that magnitude of \(\vec{A}\)?