Texas Instruments
Texas Instruments: Asa Triangle Congruence
Students construct and analyze triangles that are congruent by ASA.
Texas Instruments
Texas Instruments: Triangles
This file contains questions related to triangles. The questions can be used to asses your students' understanding of this topic in geometry.
Texas Instruments
Texas Instruments: Mc Dougal Littell Geometry: Investigate Proportionality
Students can use the TI-84 Plus family with Cabri Jr. to segment lengths in a triangle.
Texas Instruments
Texas Instruments: Angle Bisectors and Medians of Quadrilaterals
In this activity, students will construct angle bisectors and medians in quadrilaterals and explore the properties that appear to be true for four-sided figures. They may find it necessary to review the definitions and properties of...
Texas Instruments
Texas Instruments: The Orthocenter of a Triangle
Students understand that the orthocenter is the point of concurrence of the three altitudes of a triangle. They construct circumcircles and Feuerbach circles and determine the relationship between them.
Texas Instruments
Texas Instruments: Copying an Angle
Explore relationships (including congruence and similarity) among classes of two- and three-dimensional geometric objects, make and test conjectures about them, and solve problems involving them.
Analyze Math
Analyze Math: Similar Triangle Problems
The geometry tutorial investigates similar triangles. The activity has several examples with detailed solutions.
Analyze Math
Analyze Math: Congruent Triangle Problems
The geometry tutorial investigates congruent triangles. The activity has several examples with detailed solutions.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Triangulos Semejantes
Learn how to recognize and construct similar triangles with these interactive activities.
Math Open Reference
Math Open Reference: Similar Polygons and Triangles
A complete reference guide to similar triangles and polygons. It provides definitions and interactive activities that enhance further explanation.
Maths Challenge
Maths challenge.net: Corner Circle
This is a "three star" geometry problem where prior knowledge of circles and triangles is recommended to solve this circle in the corner problem.
Texas Instruments
Texas Instruments: Math Today Ballooning Inside the Box
In this activity Using the USATODAY infograph, "Ballooning inside the box", students will explore geometric relationships using similar triangles. Identifying triangles with two pairs of congruent angles to explore similarity properties...
Texas Instruments
Texas Instruments: Classifying Triangles by the Length of the Sides Using Cabri
This activity uses Cabri Jr. to classify triangles according to the length of their sides. [Requires Adobe Reader.]
Math Planet
Math Planet: Geometry: Congruent Triangles
Features a definition and a video lesson on congruent triangles with examples. [1:11]
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Congruent Polygons
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of congruent polygons.
Sophia Learning
Sophia: Using Corresponding Parts of Congruent Triangles
This lesson will demonstrate the use of CPCTC in triangle congruency proofs.
Mangahigh
Mangahigh: Shape: Recognize Congruent Shapes
Determine whether shapes are congruent or similar.
Mangahigh
Mangahigh: Shape: Right Angle in a Semi Circle Rule
Test your knowledge of the measurement of angles in a triangle.
Mangahigh
Mangahigh: Shape: Solve Problems With Similar Shapes
Test your knowledge of similar triangles and shapes.
Mangahigh
Mangahigh: Shape: 3 D Trigonometry
Test your knowledge of determing the lengths and angles of right triangles.
Khan Academy
Khan Academy: Determine Congruent Triangles
Use the triangle congruence criteria SSS, SAS, ASA, and AAS to determine that two triangles are congruent. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.