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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

The middles of the sides of any quadrilateral make a parallelogram

Area of a Triangle
Area of a Rectangle
Area of a Square
Area of a Trapezoid
Two Convex Quadrilaterals and their Areas

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

To ask and answer questions about Geometry go to the Geometry Forum.

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