Related Rates + Calculus?

Question

A particle is moving along the curve y = x^(1/2). As the particle passes through the point (4,2), its x-coordinate increases at a rate of 3 cm/s. How fast is the distance from the particle of the origin changing at this instant?

Can someone show me how to figure this out?

Answer 1

dy/dx = 1/2x^-1/2
dx/dt = 3

dy/dt = 1/6x^-1/2 = 0.12 at (4,2)

Not sure where to go from here...can you apply Pyth. Theorem?