CK-12 Foundation
Ck 12: Geometry: Angle Measures in Given Triangles
[Free Registration/Login may be required to access all resource tools.] Find the degree measure of an unknown angle in given triangles.
Khan Academy
Khan Academy: Find Angles in Triangles
Find missing angle measures using the properties of triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Varsity Tutors
Varsity Tutors: Hotmath: Algebra Review: Angle Sum Theorem
Find a quick, concise explanation of the Angle Sum Theorem. A step by step explanation of the proof is included to help you understand the theorem.
Sophia Learning
Sophia: Triangle Interior Angles Practice: Lesson 5
This lesson provides practice problems that involve the sum of the interior angles of triangles. It is 5 of 6 in the series titled "Triangle Interior Angles Practice."
Sophia Learning
Sophia: Triangle Interior Angles Practice: Lesson 1
This lesson provides practice problems that involve the sum of the interior angles of triangles. It is 1 of 6 in the series titled "Triangle Interior Angles Practice."
Texas Instruments
Texas Instruments: Angle Sum in Triangles Proof: Rotation and a Parallel Line
This investigation uses Cabri Jr. and a cleaver rotation of a triangle to "prove" that the angles in a triangle add up to 180. This could be used to reinforce triangles and paralled lines as well as introduce the concept of rotating an...
CK-12 Foundation
Ck 12: Angle Measures
[Free Registration/Login Required] Students explore the concept of finding triangle angle measurement by navigating through the interactive learning module and then answering questions that go along with the module. Students can also...
Free Math Help
Free Math Help: Angles of a Triangle Sum
The lesson discusses the angle-sum theorem. The resource consists of an explanation and practice problems with solutions.
National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...
National Council of Teachers of Mathematics
Nctm: Illuminations: Angle Sums
Students may use this computer applet to explore angle sums of triangle, quadrilaterals, pentagons and hexagons.
Homeschool Math
Homeschool Math: Equilateral, Isosceles, and Scalene Triangles
This geometry lesson defines equilateral, isosceles, and scalene triangles, and has a variety of exercises, including drawing exercises.
Khan Academy
Khan Academy: Triangle Angles Review
Reviews the rule that the interior angles of a triangle always add up to 180 degrees. Includes three practice problems.
Free Math Help
Free Math Help: Exterior Angle of a Triangle
This tutorial discusses exterior angles of a triangle. Example problems with explanations are included.
AAA Math
Aaa Math: Finding the Third Angle of a Triangle
Finding the third angle of a triangle becomes easier by the explanation and examples presented.
Other
Brown Math: Remembering Trig Identities
Faced with a large number of trigonometric identities, students tend to try to memorize them all. This site the emphasis is on understanding how the functions work and on memorizing only about a half dozen of them - all the others work...
Texas Instruments
Texas Instruments: Measuring Polygons an Introduction to Cabri Jr.
This activity is designed as an introduction to using the Carbri Jr. application on the TI-83+/84+ calculators. Students are guided through the menu system and are shown how to draw triangles, quadrilaterals and and a pentagon. Perimeter...
Varsity Tutors
Varsity Tutors: Hotmath: Graphing Calculator Practice Problems Geometry
Practice using your graphing calculator for Geometry problems. If you get stumped or if you would like to check your work, then select the View Solution button, which is located directly under each problem.
Texas Education Agency
Texas Gateway: Writing Geometric Relationships
Given information in a geometric context, students will be able to use informal arguments to establish facts about the angle sum and exterior angle of triangles, the angles created when parallel lines are cut by a transversal, and the...