A circle and a point P higher than the circle lie in the same vertical plane. A particle moves along a straight line under gravity from P to a point Q on the circle. Given that the distance travelled from P in time t is equal to 21gt2sinα, where α is the angle of inclination of the line PQ to the horizontal, give a geometrical characterization of the point Q for which the time taken from P to Q is a minimum. trigonometrygeometry solvedgeometry