Geometry

Relationships between Angles: Identifying Parallel and Perpendicular Lines

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Let's do an exercise together in which we identify parallel and perpendicular lines. This is great practice.

Special Right Triangles: 30-60-90 Triangle Side Ratios Proof

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Learn how to prove the ratios between the sides of a 30-60-90 triangle.

Algebraically Determining Segment Length: Algebraic Midpoint of a Segment

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Learn how to determining the midpoint of a line segment algebraically.

Interpreting Angles: Identify the Angle

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We're matching the visual angle with the corresponding angle measure. See if you do it on your own before listening to Sal!

Bhaskara's Proof of the Pythagorean Theorem

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This module explains an elegant visual proof of the Pythagorean Theorem developed by the 12th century Indian mathematician Bhaskara.

Angles with Triangles and Polygons: Triangle Angle - Supplementary Angle

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This problem asks you to solve for an unknown supplementary angle.

Interpreting Angles: Solving for an Angle

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Solve for a mystery angle when you know the adjacent angle, and what the combination of the mystery angle and the adjacent angle is.

Pythagorean Theorem: Solving for Unknown Sides

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This module demonstrates how to use the Pythagorean Theorem to solve for an unknown side of a right triangle.

Triangle Angles: Finding the Sums of Exterior Angles of an Irregular Pentagon

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Solve this interesting problem to find the sums of particular exterior angles of an irregular pentagon.

Axis of Symmetry: the Basics

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This module explains the axis of symmetry and how to find it, using heptagons (7-sided polygons) as an example.

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