Can anyone explain how to get this answer please and thank you. I am not good at this stuff at all

Which statement accurately describes how to perform a 90° clockwise rotation of point a (1,4) around the origin?

Find the solution on the interval [0, 2pi)

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).