The Area of a Square Inscribed in a CircleDate: 12/23/95 at 15:41:22 From: Anonymous Subject: GRE General question... HELP! I don't understand how this answer came to be! It comes from Cliff's GRE Prep Guide. Q: What is the area of a square inscribed in a circle whose circumference is 16 (pi). A: 128. Response: Huh?! How'd they do that !? Thank you very much, Thomas Date: 12/23/95 at 17:48:58 From: Doctor Elise Subject: Re: GRE General question... Hi! The circumference of a circle is (pi) times the diameter, so we know the diameter of the circle is 16. Since the square is inscribed in the circle, the diagonal distance between opposite corners is 16. a^2 + b^2 = c^2, where 'c' is the diagonal (which is 16) across the square, and forms the hypotenuse of a right triangle. Since this is a square, we know that a = b. So we know that a^2 + a^2 = (16)^2. And we can reduce this to a^2 = ((16)^2)/2 = 16 * 16/2 = 16 * 8 = 128. Since a^2 is the area of the square, we're done! -Doctor Elise, The Geometry Forum |
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