A beacon of light 200 m offshore rotates twice per minute fo

A beacon of light 200 m offshore rotates twice per minute, forming a spot of light that moves along a straight wall along the shore. How fast is the spot of light moving when the spot is at the point P, directly opposite the beacon? When it is 200 meters from point P?

an()=x/1
cos()=1/sqrt(x^2+1)
sec^2()=x^2+1

d/dt=2 rev/min=4 rad/min

x=tan()
dx/dt=sec^2() d/dt

At x=200 km

dx/dt=(200^2+1)*4=502412 km/min