Aslide is held in front of a projector, at a distance d= 74.8 cm from the screen where one can see the slide image. the image is focused on the screen by a thin lens of focal length f = 18.7 cm. a) draw a diagram showing the lens, the optical axis, the two principal rays going through the first and second focal points, and the image. b) at what distance from the slide should the lens be placed? c) is the image erect or inverted? what is the lateral magnification in this case?