# Geometry

Geometry pages:

Introduction to Geometry

Definition of Point

Definition of Line

Definition of Ray

Definition of Angle

Triangle proprieties

In a triangle the sum of the angles is 180

In a Triangle the Altitudes Intersect

In a Triangle the Bisectors Intersect

The medians of a triangle intersect

Interior angle bisector theorem

Median length theorem

The Theorem of Napoleon

Theorem of Menelaus

Pythagorean Theorem

Triangle with congruent bisectors is isosceles

Intersecting lines

The Theorem of Ceva

The Theorem of Desargues

Symmetric points and intersecting lines

Parallel lines

The Midsegment of a Triangle

The Midsegment of a Trapezoid

Equidistant Parallel Lines

Quadrilaterals

The middles of the sides of any quadrilateral make a parallelogram

Area

Area of a Triangle

Area of a Rectangle

Area of a Square

Area of a Trapezoid

Two Convex Quadrilaterals and their Areas

Circles

Definition of Circle

Circumference of a Circle

Area of a Circle

The tangents to a circle are equal in length

An inscribed circle theorem

The Incircle of a Triangle

The Incircle and Excircles of a Triangle

Four points on a circle

The Circle of Euler

Line of Euler

Triangles having the same incircle and circumcircle

The Wallace-Simson Line

The circles of Miquel

Analytic Geometry

Analytic formula for intersection of two circles

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