# Dynamic Geometry 1481: Five Tangential or Circumscribed Quadrilaterals,
Pitot Theorem, Congruence, Step-by-step Illustration

Let ABCD be a tangential or circumscribed quadrilateral (see the dynamic figure below). Lines EF
and GH intersect at P so that AEPH, BGPE, CFPG and DHPF are circumscribed quadrilaterals. Prove that EF and GH are congruent.

## Static Diagram of Geometry Problem 1481

## Poster of Geometry Problem 1481 using iPad Apps

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Classroom Resource:

Interactive step-by-step animation using GeoGebra

This step-by-step interactive illustration was created with
GeoGebra.

- To explore (show / hide): click/tap a check box.
- To stop/play the animation: click/tap the icon in the lower left corner.
- To go to first step: click/tap the "Go to step 1" button.
- To manipulate the interactive figure: click/tap and drag the blue points
or figures.

GeoGebra is free and multi-platform dynamic mathematics software for all levels of education that joins geometry, algebra, tables, graphing, statistics and calculus application, intended for teachers and students. Many parts of GeoGebra have been ported to HTML5.

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Geometry Problems

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Ten problems: 1411-1420

All Problems

Quadrilateral

Tangential or Circumscribed Quadrilateral

Incircle, Incenter, Inscribed circle

Circle

Circle Tangent Line

Pitot theorem

GeoGebra

HTML5 and Dynamic Geometry

iPad Apps

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