I am stuck on this problem because it been like 6 yrs since i took geometry and its due by 9 am. please help! Derive the thin lens equation: 1/object distance + 1/ image distance = 1/focal length for a divergent lens, using a diagram of a divergent lens (hint: use similiar triangles) I have no idea where or how to start. please show me how to do it. I know the focal length for a diverging lens is always negative and always produces a virtual image.