The angles of a triangle always sum to 180 degrees.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

The angles of a triangle always sum to 180 degrees.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

This Geogebra sketch is an explanation of how to prove that the ...

This Geogebra sketch is an explanation of how to prove that the sum of a triangle's angles is 180 degrees. It was created by Quinn Haughey at Animas High School.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

The sum of the angles of a triangle

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

gtjhgjkhg

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

This geometry lesson solves problems that determine the length of sides for ...

This geometry lesson solves problems that determine the length of sides for 30-60-90 triangles.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

This geometry lesson is Part 2 of the Proof of Heron's Formula, ...

This geometry lesson is Part 2 of the Proof of Heron's Formula, showing that the expression derived in Part 1 is identical to Heron's Formula.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

Second worksheet in a series exploring medians, altitudes, and angle bisectors of ...

Second worksheet in a series exploring medians, altitudes, and angle bisectors of triangles.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

Just as rigid motions are used to define congruence in Module 1, ...

Just as rigid motions are used to define congruence in Module 1, so dilations are added to define similarity in Module 2. To be able to discuss similarity, students must first have a clear understanding of how dilations behave. This is done in two parts, by studying how dilations yield scale drawings and reasoning why the properties of dilations must be true. Once dilations are clearly established, similarity transformations are defined and length and angle relationships are examined, yielding triangle similarity criteria. An in-depth look at similarity within right triangles follows, and finally the module ends with a study of right triangle trigonometry.

- Subject:
- Geometry
- Material Type:
- Module
- Provider:
- New York State Education Department
- Provider Set:
- EngageNY

Conditions of Use:

Remix and Share

Students find the area of regular polygons, recalling what they already know ...

Students find the area of regular polygons, recalling what they already know about the area of geometric shapes and generalizing a formula for any regular polygon.

Key Concepts

Students will recall what they already know about the area of geometric shapes and apply that to find the area of regular polygons. Any regular polygon can be divided into congruent isosceles triangles. If the length from the center to the midpoint of a side (the apothem ) is known, the area of the triangles and the area of the polygon can be found. Students will see the similarities between the area of a polygon and derive the formula for the area of a circle.

Goals

Review area of triangles, rectangles, and parallelograms.

Find the area of regular polygons.

Generalize an area formula for any regular polygon.

ELL: This lesson offers students a rich opportunity to learn academic vocabulary. Display the new terms in writing somewhere visible in the classroom so that you can refer to them. Allow ELLs to use their bilingual dictionaries to help with understanding the terms. When possible, have ELLs discuss the terms in their language of choice with other ELLs who share the same primary language.

Conditions of Use:

Remix and Share

This is the second version of a task asking students to find ...

This is the second version of a task asking students to find the areas of triangles that have the same base and height. This presentation is more abstract as students are not using physical models.

- Subject:
- Mathematics
- Geometry
- Material Type:
- Activity/Lab
- Provider:
- Illustrative Mathematics
- Provider Set:
- Illustrative Mathematics
- Author:
- Illustrative Mathematics

Conditions of Use:

Remix and Share

Angle Properties of Circles - Property 2

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

An exploration on if SSS guarantees that two triangles are congruent.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

An exploration on if SSS guarantees that two triangles are congruent.

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

This geometry lesson continues the discussion of similar triangles and the use ...

This geometry lesson continues the discussion of similar triangles and the use of ratios to determine lengths of corresponding sides.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

Salman Khan presents more angle game problems for students to solve.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

This geometry lesson provides the proof that the centroid is 2/3 of ...

This geometry lesson provides the proof that the centroid is 2/3 of the way along every median of a triangle.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

Equilateral triangle DAN has point X inside it. Where should point X ...

Equilateral triangle DAN has point X inside it. Where should point X be placed so that the three perpendicular Segments to the three sides of the triangle have a minimum total length?

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

This geometry lesson demonstrates how to find the area of a rhombus ...

This geometry lesson demonstrates how to find the area of a rhombus from circumradii of triangles.

- Subject:
- Geometry
- Material Type:
- Lecture
- Provider:
- Khan Academy
- Provider Set:
- Khan Academy
- Author:
- Khan, Salman

Conditions of Use:

Remix and Share

Construct room using triangles

- Subject:
- Geometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube

Conditions of Use:

Remix and Share

3 triangles controlled by the same slider. Ask students to calculate the ...

3 triangles controlled by the same slider. Ask students to calculate the 3 trig ratios for the triangles.

- Subject:
- Geometry
- Trigonometry
- Material Type:
- Simulation
- Provider:
- GeoGebra
- Provider Set:
- GeoGebraTube