Tangential Quadrilateral

Author

Eric W. Weisstein
August 13, 2003

This notebook downloaded from http://mathworld.wolfram.com/notebooks/PlaneGeometry/TangentialQuadrilateral.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/TangentialQuadrilateral.html.

©2005 Wolfram Research, Inc. except for portions noted otherwise

Graphic

a={.9,2.6,4.8,5.3};
Show[Graphics[{
{Dashing[{.02,.02}],Circle[{0,0},1],TangentialQuadrilateralNormals[a]},
TangentialQuadrilateral[a]
}],AspectRatio->Automatic]

Inradius

Solve[Sqrt[4p^2q^2-(b^2+d^2-a^2-c^2)^2]/4==r (a+b+c+d)/2,r]

FullSimplify[((Sqrt[-(((-(a^2)+(b^2)-(c^2)+(d^2)))^2)+4 (p^2) (q^2)])/(2 (a+b+c+d)))/.{c->s-a,d->s-b}]