# circle that touch quadrantal internally

I want to know how to construct circle that touch quadrantal(1/4 part of circle) internally.

I spend several hours for solving this problem but I have no luck.

I attached the picture what I've tried

could somebody please tell me how to construct step by step?

thanks in advanced

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What's the radius of the smaller circle? – J. M. Sep 29 '11 at 4:48
it's euclid construction. none of values are provided – kim taeyun Sep 29 '11 at 4:55
@J.M.: I'm assuming kim want's the inscribed circle – Codie CodeMonkey Sep 29 '11 at 5:02
Oh, like this? – J. M. Sep 29 '11 at 10:26

## 1 Answer

Construct the tangent line of the quadrantal at the midpoint of it's arc. Intersect that with the radial lines of the quadrantal. Since the inner circle must be tangent to both the outer circle and the constructed tangent at the same point, the problem is reduced to finding the inscribed circle of the triangle.

The inscribed circle of the triangle has a center at the intersection of the angle bisectors of the triangle.

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"the tangent line of the quadrantal at the midpoint of it's arc" - to add detail: bisect the right angle, and from the angle bisector, construct a perpendicular through the intersection of the arc and the angle bisector. – J. M. Sep 29 '11 at 5:02