Purple Math
Purplemath: Angles of Inclination and Declination
Explains the terminology for angles of elevation, depression, inclination, and declination. Demonstrates how to 'translate' exercises into triangles and equations.
Math Planet
Math Planet: Geometry: Parallelogram, Triangles Etc
Resource examines the area of geometric solids through examples and a video lesson. [0:39]
University of Georgia
University of Georgia: Inter Math: Altitude of a Triangle
This site gives a description along with a visual representation of the altitude of a triangle. There are links to related terms, everyday examples, challenging problems, more information, and the interactive check point involving...
Other
Dma: Geometria Computacional
Use these interactive applications to learn about the Delaunay triangulations and the Voronoi diagrams.
Other
Edumat: Geometria Interactive
In this section different interactive activities are presented which can be used as supplementary material to traditional classroom and allow for interactive study of mathematics.
TED Talks
Ted: Ted Ed: How Many Ways Are There to Prove the Pythagorean Theorem?
Betty Fei details these three famous Pythagorean theorem proofs.
Illustrative Mathematics
Illustrative Mathematics: A sse.b.4: Triangle Series
The purpose of this task is to emphasize the adjective "geometric" in the "geometric" series, namely, that the algebraic notion of a common ratio between terms corresponds to the geometric notion of a repeated similarity transformation....
Illustrative Mathematics
Illustrative Mathematics: 4.g Are These Right?
The purpose of this task is for students to measure angles and decide whether the triangles are right or not. Aligns with 4.G.A.2.
Illustrative Mathematics
Illustrative Mathematics: 8.g Circle Sandwich
Eighth graders are presented with a drawing of a large square inscribed by a circle which is itself inscribed by a second square. They are asked to find the area of the circle outside the smaller square and compare it to the area of the...
CK-12 Foundation
Ck 12: Elem Math: Identifying Rectangles, Squares, Circles, and Triangles
[Free Registration/Login may be required to access all resource tools.] The video discusses a brief overview of circles, rectangles, squares, and triangles and helps students determine which shape is shown and why. The video is followed...
CK-12 Foundation
Ck 12: Geometry: Triangle Sum Theorem Grades 9 10
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the Triangle Sum Theorem, and how to use it.
CK-12 Foundation
Ck 12: Geometry: Congruent Triangles
[Free Registration/Login may be required to access all resource tools.] This concept teaches students what it means for two triangles to be congruent and how to identify corresponding parts of congruent triangles. Students examine guided...
CK-12 Foundation
Ck 12: Trigonometry: Law of Cosines
[Free Registration/Login may be required to access all resource tools.] Use Law of Cosines and Law of Sines in different triangle situations.
CK-12 Foundation
Ck 12: Geometry: Exterior Angles Theorems
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the sum of exterior angles for any polygon and the relationship between exterior angles and remote interior angles in a triangle....
CK-12 Foundation
Ck 12: Geometry: Triangle Sum Theorem Grade 7
[Free Registration/Login may be required to access all resource tools.] Recognize the sum of the interior angles of a triangle as 180 degrees.
CK-12 Foundation
Ck 12: Geometry: Triangle Sum Theorem Grades 8 10
[Free Registration/Login may be required to access all resource tools.] Recognize the sum of the interior angles of a triangle as 180 degrees.
Purple Math
Purplemath: Special Angle Values: 30 60 90 and 45 45 90 Triangles
Explains a simple pictorial way to remember basic reference angle values. Provides other memory aids for the values of trigonometric ratios for these "special" angle values, based on 30-60-90 triangles and 45-45-90 triangles.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.
CK-12 Foundation
Ck 12: Geometry: Triangle Relationships Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews terminology for triangles, triangle properties, different types of triangles, and interior and exterior angle theorems.
CK-12 Foundation
Ck 12: Geometry: Area and Perimeter of Triangles
[Free Registration/Login may be required to access all resource tools.] In this lesson students use formulas and given information to figure out the dimensions and the area of different triangles. Students examine guided notes, review...
CK-12 Foundation
Ck 12: Geometry: Triangle Area Grades 6 7
[Free Registration/Login may be required to access all resource tools.] Find the areas of triangles given their base and height dimensions.
CK-12 Foundation
Ck 12: Trigonometry: General Solutions of Triangles
[Free Registration/Login may be required to access all resource tools.] A summary of when to use the law of cosines or the law of sines to solve triangles.
CK-12 Foundation
Ck 12: Geometry: Isosceles Triangles
[Free Registration/Login may be required to access all resource tools.] Apply the properties of isosceles triangles.
CK-12 Foundation
Ck 12: Geometry: Isosceles Triangles
[Free Registration/Login may be required to access all resource tools.] This concept will teach students the properties of isosceles triangles and how to apply them to different types of problems.