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March 20th, 2017, 11:42 PM   #1
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Area of circle

Does anybody know how to find the area of the larger circle knowing only that the radius of the smaller inner circles is equal to 5.2 ? thanks in advance,
Attached Images circles-within-circle (2).png (3.4 KB, 10 views) March 21st, 2017, 12:55 AM #2 Senior Member   Joined: Sep 2015 From: USA Posts: 2,427 Thanks: 1314 draw a square connecting the centers of the smaller circles. It has side length $2r$ It's diagonal has length $d = 2\sqrt{2}r$ The diameter of the larger circle is $D = 2r + d = 2r(1+\sqrt{2})$ and it's radius $R = r(1+\sqrt{2})$ with area $A = \pi R^2 = \pi r^2(1+\sqrt{2})^2 = \pi r (3+2\sqrt{2})$ $A = (3+2\sqrt{3})\pi (5.2) = 30.3078 \pi$ Thanks from topsquark Tags area, circle, trigonometry Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post skimanner Math 12 July 8th, 2016 07:55 AM matemagia Calculus 3 January 31st, 2015 05:39 AM yeoky Algebra 4 May 3rd, 2014 01:06 AM Jamers328 Calculus 5 August 6th, 2012 01:02 PM gus Algebra 1 April 17th, 2011 04:25 PM

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