Recent content by J.Friedrich

i have a parabolic mirror with equation x=-1/2y^2 there are 5 parallel rays coming into the parabolic mirror at y=2,y=1,y=0,y=-1,y=-2 (a) find the focal length i found the equation f=D^2/(16c) where D is the diameter, and c is the depth. this gives me a focal length of (1/2) i was...