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 _________________________________ 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 __________________________________ 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 _______________________________________ Final Exams and Video Playlists: https://www.video-tutor.net/ Full-Length Videos and Worksheets: https://www.patreon.com/MathScienceTutor/collections