Question

You are taking a photograph of a poster on the wall of your dorm room, so you can't back away any farther than 3.9 m to take the shot. The poster is 0.80 m wide and 1.3 m tall, and you want the image to fit in the 24  36 mm frame of the film in your camera. What is the longest focal length lens that will work? (Include the sign.)
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