Instructional Video2:07
CK-12 Foundation

SSS Similarity Theorem: Lesson

9th - 11th Standards
Judging by the sides, things appear similar. A portion of a larger playlist on geometry introduces the Side-Side-Side Similarity Theorem. The video shows how to use the lengths of sides to determine whether triangles are similar.
Instructional Video2:56
CK-12 Foundation

Parallel Lines and Transversals: Lesson

7th - 11th Standards
Segment transversals proportionally. Given a diagram with three parallel lines and two transversals, the narrator of a short video points out the parallel lines cut the transversals proportionally. The portion of a long playlist on...
Instructional Video4:02
CK-12 Foundation

Classifying Parallelograms: Lesson

8th - 11th Standards
Properly organize parallelograms. Given special parallelograms, the narrator of a short video explains the properties of each. The section of a playlist on geometry uses the properties to classify the special parallelograms.
Instructional Video6:07
CK-12 Foundation

Medians: Examples

8th - 11th Standards
Balance the knowledge of intersecting medians. Using examples, the portion of a geometry playlist introduces the centroid. A video describes the property of the location of the triangle medians' point of concurrency. 
Instructional Video3:07
CK-12 Foundation

Perpendicular Bisectors: Lesson

8th - 11th Standards
Get right up and split it in half. Using a diagram, the video provides the definition of a perpendicular bisector. The portion in a playlist on basic geometry explains perpendicular bisector of a segment and of triangle sides properties.
Instructional Video3:15
CK-12 Foundation

Arcs in Circles: Lesson

6th - 11th Standards
Taking a major look at arcs is not minor. A segment of an extensive playlist on geometry introduces the concept of an arc in a circle. The resource demonstrates how to find the measure of an arc and defines special types of arcs.
Instructional Video3:18
CK-12 Foundation

Triangle Proportionality: Lesson

7th - 11th Standards
Look at proportionality from a parallel perspective. A section of an expansive geometry playlist introduces the Triangle Proportionality Theorem. Using the theorem, the video shows how to determine missing measurements in triangles.
Instructional Video2:35
CK-12 Foundation

Triangle AA Similarity: Lesson

7th - 11th Standards
Two sets of congruent angles leads to three. Using diagrams of two triangles, the presentation intuitively shows that if two sets of angles are congruent, the third set is too. The portion of a geometry playlist uses that information to...
Instructional Video4:29
CK-12 Foundation

Classifying Quadrilaterals in the Coordinate Plane: Lesson

8th - 11th Standards
Coordinate the classification of quadrilaterals. Given the definitions of special quadrilaterals, a portion of a geometry playlist highlights ways to classify a quadrilateral. The video takes information from figures on a coordinate...
Instructional Video3:41
CK-12 Foundation

Parallelograms: Lesson

8th - 11th Standards
Properties spawn from parallel sides. With the aid of diagrams, the presentation shows the different properties of parallelograms. The segment of an extensive geometry playlist lists the properties that using the parallel sides of a...
Instructional Video3:45
CK-12 Foundation

Altitudes: Examples

6th - 11th Standards
Find the location of altitudes—from any elevation! The video presents the definition of an altitude of a triangle. By drawing examples, the segment of a larger geometry playlist highlights the location of altitudes of various triangle...
Instructional Video3:51
CK-12 Foundation

ASA and AAS Triangle Congruence Lesson

8th - 11th Standards
The location of the side makes a difference. One of the videos in a geometry playlist introduces angle-side-angle and angle-angle-side congruence relationships. Using drawings, the video shows how these two congruence statements are...
Instructional Video4:59
CK-12 Foundation

Chords in Circles: Lesson

8th - 11th Standards
Strike a chord with four theorems. The segment of a playlist on geometry introduces four basic theorems about chords in a circle. Theorems include the relationships between diameters and chords, congruent chords and arcs, and congruent...
Instructional Video3:35
CK-12 Foundation

Inscribed Similar Triangles: Lesson

6th - 12th Standards
Create similar triangles with a little altitude. A section of an extensive playlist on basic geometry discusses how an altitude of a right triangle creates similar triangles. Using the theorem, the presentation finds unknown side...
Instructional Video2:43
CK-12 Foundation

Proportions with Angle Bisectors: Lesson

8th - 11th Standards
Half at one end becomes proportional on the other. As part of a basic geometry playlist, the video introduces the Angle Bisector Theorem. The presentation uses the theorem to find missing lengths in triangles.
Instructional Video2:30
CK-12 Foundation

SAS Similarity Theorem: Lesson

7th - 11th Standards
When given two sides and an angle, make similar triangles. The video describes the SAS Similarity Theorem. Using the theorem, the segment of a larger geometry playlist determines whether two triangles are similar.
Instructional Video2:40
CK-12 Foundation

The Third Angle Theorem: Lesson

8th - 11th Standards
If two sets of angles are equal, the third set is too. An informative portion of a playlist on geometry develops the Third Angle Theorem for triangles. Using the theorem, the presenter shows how to determine the measure of missing angles...
Instructional Video3:25
CK-12 Foundation

Proving a Quadrilateral Is a Parallelogram: Lesson

8th - 11th Standards
If it has the properties of a parallelogram, it must be a parallelogram. A segment of a playlist on geometry presents the converses of the properties of a parallelogram. Given a quadrilateral with specific characteristics, the video...
Instructional Video4:04
CK-12 Foundation

Angle Bisectors: Lesson

8th - 11th Standards
Apply bisectors and distances to angles. Using the definition of an angle bisector, a portion of a geometry playlist draws a diagram showing the angle bisector. The video details properties of an angle bisector and their converses....
Instructional Video2:28
CK-12 Foundation

Midsegment Theorem: Lesson

8th - 11th Standards
Use half the length to connect the midpoints. A section of a playlist on geometry introduces the concept of a midsegment of a triangle and how to find it. The video states the properties of the midsegment which make up the Midsegment...
Instructional Video3:02
CK-12 Foundation

Isosceles Triangles: Lesson

8th - 11th Standards
Two sides give us two angles. A segment of a playlist on basic geometry revisits isosceles triangles. The presentation explains several properties and theorems related to isosceles triangles.
Instructional Video3:20
CK-12 Foundation

SAS Triangle Congruence: Lesson

8th - 11th Standards
SAS is not just a spy organization. A section of an extensive geometry playlist introduces a way to show two triangles are congruent, SAS. Using diagrams, the video provides an explanation by showing only one triangle is formed with two...
Instructional Video2:42
CK-12 Foundation

Congruent Triangles: Lesson

9th - 12th Standards
Given two congruent triangles, the resource provides the definition of congruent triangles and marks the corresponding parts. The portion of a basic geometry playlist shows the triangles are congruent by moving one on top of the other...
Instructional Video4:47
CK-12 Foundation

Exterior Angles Theorems: Lesson

9th - 12th Standards
Use the inside to find the outside. The resource presents two theorems dealing with exterior angles of a triangle. Using the two theorems, the segment from a larger geometry playlist works problems to solve for angle measures.