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Fancy quadrilateral (Posted on 2019-10-25) Difficulty: 4 of 5
The radii of the incircle and the circumcircle of a quadrilateral are 7 and 12. Find the distance between the centers of the two circles.

No Solution Yet Submitted by Danish Ahmed Khan    
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Solution re(2): the right starting point? - kite solution | Comment 3 of 4 |
(In reply to re: the right starting point? - kite solution by Brian Smith)

I tried starting with an isosceles trapezoid, which always has a circumcircle and can be easily adjusted to have an incircle.  This proved difficult so I switched and also went with a right kite.


With sides a and b we have a^2+b^2=24^2 and ab/(a+b)=7

From which a+b=32, ab=224 and the distance sought satisfies

d^2=(7-a/2)^2+(7-b/2)^2
d^2=18
d=sqrt(18)=3sqrt(2)



  Posted by Jer on 2019-10-26 13:49:50
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