This geometry video tutorial explains how to prove parallel lines using two column proofs. This video contains plenty of examples and practice problems for you to learn the concept.
Triangle Congruence - SSS, SAS, ASA: https://www.youtube.com/watch?v=jWHOF6cFbpw
CPCTC - 2 Column Proofs With Triangles:
https://www.youtube.com/watch?v=eq1frp_ZyP8
Hypotenuse Leg Theorem - HL Postulate:
https://www.youtube.com/watch?v=DKSTjS0n3mY
Detour Proofs - Double Triangle Congruence:
https://www.youtube.com/watch?v=1HOrB5yvEl0
The Midpoint Formula:
https://www.youtube.com/watch?v=pzDfd8NXRXk
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Missing Diagrams - 2 Column Proofs:
https://www.youtube.com/watch?v=IaqzuGweGZ8
Right Angle Theorem - SSS & SAS:
https://www.youtube.com/watch?v=FRbFMp8mg1s
Perpendicular Bisector Theorem:
https://www.youtube.com/watch?v=xyNBZuUjmSE
Altitude, Median, Midpoint & P. Bisector:
https://www.youtube.com/watch?v=SyzkgBjXtIs
Parallel & Perpendicular Lines - Slope:
https://www.youtube.com/watch?v=bq3fKZVTflU
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Indirect Proofs - Example Problems:
https://www.youtube.com/watch?v=GawWGpnjy1c
The Exterior Angle Theorem:
https://www.youtube.com/watch?v=ndqxxAUDF5Y
Exterior Angle Inequality Theorem:
https://www.youtube.com/watch?v=rfMZwrq-wL8
Polygons:
https://www.youtube.com/watch?v=E_-3ulbtcLk
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https://www.video-tutor.net/
Full-Length Videos and Worksheets:
https://www.patreon.com/MathScienceTutor/collections