Chapter 3: Triangle Theorems

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Some links are repeated for use with more than one lesson.

3.1  The Triangle Sum Theorem

http://www.conservapedia.com/Triangle_Angle_Sum_Theorem
This page defines the Triangle Sum Theorem.

http://www.math.csusb.edu/courses/m129/tri180.html
This page contains a demonstration showing that the interior angles of a triangle add up to 180°.

3.2  Inequalities in Geometry

3.3  The Triangle Inequality Theorem

http://www.mathopenref.com/triangleinequality.html
This page contains an explanation of the triangle inequality theorem with a movable triangle to demonstrate.

http://www.quia.com/cm/94303.html?AP_rand=1353796656
This site has a game to practice determining if a triangle could exist based on the length of its sides.

3.4  Congruent Triangles

http://www.freemathhelp.com/feliz-congruent-triangles.html
This page defines congruent triangles and the qualifications for them and lists the methods for proving congruency.

http://argyll.epsb.ca/jreed/math9/strand3/triangle_congruent.htm
This site explains congruent triangles and explains the differences between similarity and congruency.

3.5  Proving Triangles Congruent

http://www.freemathhelp.com/Lessons/Geometry_Proving_Triangles_Congruent_BB.htm
This site contains a video tutorial with notes on proving triangles congruent.

http://www.sparknotes.com/math/geometry2/congruence/section2.rhtml
This page details the different methods on how to prove triangles congruent.

3.6  Using Congruent Triangles

http://www.algebralab.org/practice/practice.aspx?file=Geometry_UsingCongruentTriangles.xml
This site contains an online quiz about using congruent triangles.

3.7  Isosceles and Right Triangle Theorems

http://www.themathpage.com/atrig/isosceles-right-triangle.htm
This page discusses the isosceles right triangle theorem and has interactive questions.

3.8  Altitudes, Medians, and Bisectors

http://www.bbc.co.uk/scotland/education/bitesize/higher/maths/geometry/the_straight_line8_rev.shtml
This page contains definitions of altitudes, medians, and perpendicular bisectors.

http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Altitudes-Medians-and-Angle-Bisectors.topicArticleId-18851,articleId-18787.html
This site explains altitudes, medians, and bisectors and has pictures of each.