Proof by contradiction that if two lines cut by a transversal create congruent corresponding angles then the lines are parallel. [5:18]

Explains how to determine the area of a pentagonal shaded region in a triangle. The triangle that is broken into multiple similar and congruent triangles. [10:07]

Solving for unknown angle measures using knowledge of different angle relationships and the triangle sum theorem. Continuation of Angle Game video. [9:49]

Solving for unknown angle measures using knowledge of different angle relationships and the triangle sum theorem. [9:01]

Explains how to identify and use similar triangles in order to determine unknown side lengths in two given diagrams. Each diagram also applies knowledge of angles formed when parallel lines are cut by a transversal. [7:37]

Explains how to determine unknown side lengths in a diagram that involves similar triangles where the two triangles share a side and the shared side corresponds to two different sides in each triangle. [6:05]

Proof that the sum of the angles in a triangle is 180 using the relationship of angles formed when parallel lines are cut by a transversal. This video also appears in the Geometry: Triangles strand. [6:31]

Explains how to use given triangle congruency statements to determine the unknown measures of all angles in a diagram where one large triangle is divided into three congruent triangles. [4:35]

Proof that if the legs of an isosceles triangle are congruent then the base angles are congruent and vice versa using triangle congruency postulates. The proof is written as a two-column proof. [9:03]

Explains the difference between congruent triangles and similar triangles. Introduces the idea of scale factors. [9:17]

In this video tutorial [11:29], the instructor explains how to use triangle congruence to identify measures of corresponding sides and angles in triangles. Defines side-side-side (SSS) postulate. Practice problems available.

Explains how to determine the area of a pentagonal shaded region in a triangle. The triangle that is broken into multiple similar and congruent triangles.

Solving for unknown angle measures using knowledge of different angle relationships and the triangle sum theorem.

Solving for unknown angle measures using knowledge of different angle relationships and the triangle sum theorem.

Explains how to determine unknown side lengths in a diagram that involves similar triangles where the two triangles share a side and the shared side corresponds to two different sides in each triangle.

Indirect measurement using shadows and proportions is explored in this video lesson. The tutorial includes a very detailed example of the concept.

Find unknown information about similar figures by using similar figures. Assess learning with a quiz.

Video proving that the sum of the measures of the angles in a triangle are 180.

Explains what it means for two triangles to be similar. Diagram of similar triangles is created with two parallel lines cut by two transversals.

Explains how to identify and use similar triangles in order to determine unknown side lengths in two given diagrams.

Take a look at this tutorial to see how to find all the missing angle measurements by identifying vertical, corresponding, adjacent, and alternate exterior angles. [4:43]

This video explains the relationship between the measures of angles formed when parallel lines are cut by a transversal.

Identifies and defines the types of angles formed by parallel lines cut by a transversal and the relationship of their measures.

Explains how to determine the measures of all the angles formed when parallel lines are cut by a transversal based on the measure of one angle. Explains how to use corresponding congruent angles to determine if lines cut by a transversal...