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PROBLEM 253 This problem was suggested by Dr. Max Forester, a recent visitor to the our department. Thanks, Max!Take a piece of paper, draw a circle of radius 1 on it, and fix a point P in its interior. Take a point Q on the circumference of the circle and fold the paper over until Q meets P; see the figure on the left below. Draw a line along the crease in the paper. Do this for each point on the circumference. These lines enclose a region on the paper; that is; they form the envelope of tangent lines to a curve in the plane. In the figure on the right below, a sampling of these "crease lines" are shown. What is the shape of this region? Please explain your answer clearly. (Hint: Before you start on this problem, cut a circle out of paper -- or use a paper plate -- and create some examples for yourself.)   You are visitor
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