Related Rate Problem?

Question

An airplane flies in level flight at constant velocity, eight miles above the ground. (Assume the earth is flat.) The flight path passes directly over a point P on the ground. The distance from the plane to P is decreasing at the rate of 4 miles per minute at the instant when this distance is 10 miles. Compute the velocity of the plane in miles per hour.

Answer 1

It is a vector problem. Va = Vb + Va/b.

You know Vb = 0, You know Va/b = -4 miles/minute.

You know the direction of Va.

You know the direction of Va/b.

Seems pretty easy to me.