The shadow of a pendulum cast on a flat board moves on a straight line. By placing the x-axis on the straight line with the origin at the middle of the total path, the x-coordinate of the shadow is given by the following function: x(t) = 45cos(πt), where t is in seconds and x is in centimeters. show answer No Attempt 25% Part (a) Find the speed, in centimeters per second, of the shadow at t = 1/4 s.