3) Consider a Lambertian plane in three dimensions defined by the equation 7x+50y+z+2=0 a) What is the surface gradient (p,q) for the plane? b) Suppose that the plane is in a dark room with a single point light source. Consider the point P=(0,0,2) on the plane. Determine the location (x,y,z) where we should put the point light source so that the light source is a distance 20 from the point P and the reflected radiance from P in the direction of (0,0,0) is as large as possible