Angles of Triangles Videos - Free Educational Videos for Students in K - 12

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This page provides a list of educational videos related to Angles of Triangles. You can also use this page to find sample questions, apps, worksheets, lessons , infographics and presentations related to Angles of Triangles.


Find missing angles of triangles


By Khan Academy

Sal combines what we know about isosceles triangles and parallel lines with the power of algebra to solve the angles of an isosceles triangle.

Find missing angles of triangles


By Khan Academy

Sal solves the following problem: The measures of two angles of an isosceles triangle are 3x+5 and x+16. Find all possible values of x.

Area Of A Non-Right Angle Triangle


By VividMaths.com

Area Of A Non-Right Angle Triangle proof

Triangle angle example 1 | Angles and intersecting lines | Geometry | Khan Academy


By Khan Academy

Figuring out angles in a triangle. A little about exterior angles being the sum of the remote interior angles

Triangle angle example 1 | Angles and intersecting lines | Geometry | Khan Academy


By Khan Academy

Figuring out angles in a triangle. A little about exterior angles being the sum of the remote interior angles

Proving the Sum of Measures of Angles in a Triangle are 180


By Khan Academy

This video gives us a walkthrough of the proof that the angle measures of the angles of a triangle add up to 180. This proof requires us to draw in a line on our own (specifically, one that is parallel to one side of the triangle, but it could be any side). Then we can treat the two non-parallel sides as transversals.

Angle bisector theorem proof | Special properties and parts of triangles | Geometry | Khan Academy


By Khan Academy

In this video, we'll quickly review the angle bisector theorem, and then we'll see how it's proven. We prove it by extending a parallel line to one of the triangle's legs. That tells us information about the interior angles!

Geometry -- Lesson 4.3 -- Congruent Triangles


By MisterRutter

This geometry lesson explains congruent triangles: triangles with the same measure sides and angles.

Find missing angles of triangles


By Khan Academy

Three example problems involving isosceles and equilateral triangles (partly taken from Art of Problem Solving, by Richard Rusczyk).

Proving Triangles are Similar - YourTeacher.com - Geometry Help


By yourteachermathhelp

Students learn the following theorems related to similar triangles. If an angle of one triangle is congruent to an angle of another triangle, and the lengths of the sides that include each angle are in proportion, then the triangles are similar (Side-Angle-Side Similarity Theorem, or SAS Similarity Theorem). If the lengths of the sides of two triangles are in proportion, then the triangles are similar (Side-Side-Side Similarity Theorem, or SSS Similarity Theorem). Students are then asked to determine whether given triangles are similar based on these theorems.

Introduction to Geometry - 21 - Identifying Similar Triangles AA


By thenewboston

"AA" stands for "Angle-Angle." This means that if two triangles are known to have two corresponding angles that are equal in measure, then the two angles are similar.

Triangle Similarity - AA SSS SAS & AAA Postulates, Proving Similar Triangles, Two Column Proofs


By The Organic Chemistry Tutor

This geometry video tutorial provides a basic introduction into triangle similarity. it explains how to use two column proofs in order to prove if two triangles are similar using the mostly the AA postulates. Other triangle similarity postulates mentioned are the AAA, SSS, and SAS postulates. Theorems used in this video include the base angle theorem, theorems associated with parallel lines, alternate interior angle theorem, vertical angles, reflexive property, definition of an altitude, right angle congruence, and more. This geometry video contains plenty of examples and practice problems on triangle similarity.

Proving Triangles are Congruent - YourTeacher.com - Math Help


By yourteachermathhelp

For a complete lesson on proving triangles are congruent, go to http://www.yourteacher.com - 1000+ online math lessons featuring a personal math teacher inside every lesson! In this lesson, students learn the following postulates related to congruent triangles and triangle proofs. If the three sides of one triangle are congruent to the three sides of another triangle, then the triangles are congruent (Side-Side-Side or SSS). If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent (Side-Angle-Side or SAS). If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the triangles are congruent (Angle-Side-Angle or ASA). Students are then asked to determine whether given triangles are congruent, and name the postulate that is used.

7.1 Triangle Application Theorems (Lesson)


By AutenMath

A lesson explaining a.) why the sum of the measures of a triangle equals 180 degrees b.) the relationship between exterior angles and remote interior angles of a triangle and c.) the midline theorem

45-45-90 triangles | Right triangles and trigonometry | Geometry | Khan Academy


By Khan Academy

Video uses an electronic black board with different colored pens. Introduction to 45-45-90 Triangles, these can also be called right triangles because of the 90 degree measurement. These triangles are special because if two angles of a triangle are equal the one side they don’t share is going to be equal. This then goes on to explain Pythagorean Theorem, Side A squared + Side B squared = Side C squared, side C is the hypotenuse or the side that is shared in a triangle. The narrator goes on to explain how to solve, using square roots. This video is for middle school students.

Congruent Figures | MathHelp.com


By MathHelp.com

This lesson covers dividing integers. Students learn to divide integers using the following rules. A positive divided by a positive equals a positive. For example, +20 divided by +2 = +10. A positive divided by a negative equals a negative. For example, +20 divided by -2 = -10. A negative divided by a positive equals a negative. For example, -20 divided by +2 = -10. And a negative divided by a negative equals a positive. For example, -20 divided by -2 = +10. In other words, if the signs are the same, the quotient is positive, and if the signs are different, the quotient is negative. Note that any integer divided by zero is undefined. For example, +4 divided by 0 = undefined. And zero divided by any integer (other than zero) is zero. For example, 0 divided by +4 = 0.