A particle travels clockwise on a circular path of diameter D, monitored by a sensor on the

Question:

A particle travels clockwise on a circular path of diameter D, monitored by a sensor on the circle at point P; the other endpoint of the diameter on which the sensor lies is Q (see figure). Let θ be the angle between the diameter PQ and the line from the sensor to the particle. Let c be the length of the chord from the particle's position to Q.

a. Calculate dθ/dc.

b. Evaluate $do dc \c=0$