This geometry video provides a basic introduction into triangles. It explains how to calculate the measure of an interior angle of a triangle as well as the exterior angle. The sum of all three interior angles is 180. The exterior angle is the sum of the two remote interior angles according to the exterior angle theorem. In addition, this video explains how to calculate the length of the midsegment of a triangle. It contains plenty of examples and practice problems.
Polygons:
https://www.youtube.com/watch?v=E_-3ulbtcLk
Quadrilaterals:
https://www.youtube.com/watch?v=ogcH3eM5beM
Skew Lines:
https://www.youtube.com/watch?v=cemF45vNOhg
Points, Lines, Planes, & Segments:
https://www.youtube.com/watch?v=dDWjhRfBsKM
Number of a Diagonals In a Polygon:
https://www.youtube.com/watch?v=jZYL2TUrYSw
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Ratios and Proportions - Means Extreme:
https://www.youtube.com/watch?v=tFCrFa0mDi4
Similar Triangles:
https://www.youtube.com/watch?v=YiFwvAFk-xs
Similar Triangles - Enlargement Ratios:
https://www.youtube.com/watch?v=r7m424e3Kdc
Triangle Similarity - SSS, SAS, & AAA:
https://www.youtube.com/watch?v=VXlFEilh-cw
Triangle Proportionality Theorem:
https://www.youtube.com/watch?v=EQpguitDfGU
Altitude on Hypotenuse Theorem:
https://www.youtube.com/watch?v=RiTp3vyWe0o
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Pythagorean Theorem:
https://www.youtube.com/watch?v=d8EA5TxGzcY
The Distance Formula:
https://www.youtube.com/watch?v=YDvUy5VYm9E
Distance Between 2 Points - 3D:
https://www.youtube.com/watch?v=0c6cP2zLC2c
Final Exams and Video Playlists:
https://www.video-tutor.net/
Full-Length Videos and Worksheets:
https://www.patreon.com/MathScienceTutor/collections