Answer: So mg = Fg or 271.7N. We can break up this vector into two components. The x & y. Since we’re only interested in the magnitude of the box moving down the plane. Try mg sin theta or 271.7N(sin43.9 degrees). Make sure the calculator is in degrees not radians. If it is not asking for the magnitude, rather the actual vector quantity, make the answer value negative, because the box is sliding down the incline.