Lines: Parallel and Perpendicular
http://www.clackamasmiddlecollege.org/documents/
http://www.fengerhighschool.org/ourpages/auto/2010/3/21/54491360/parallel%20and%20perpendicular%20lines.pdf
http://www.purplemath.com/modules/slope2.htm
http://www.mathsisfun.com/algebra/line-parallel-perpendicular.html
http://www.youtube.com/watch?v=Rew54K6mYUo
http://www.regentsprep.org/Regents/math/ALGEBRA/AC3/Lparallel.htm
My link : http://animoto.com/play/v74LVRGRSVicGwYZeHWspQ
http://www.clackamasmiddlecollege.org/documents/
http://www.fengerhighschool.org/ourpages/auto/2010/3/21/54491360/parallel%20and%20perpendicular%20lines.pdf
http://www.purplemath.com/modules/slope2.htm
http://www.mathsisfun.com/algebra/line-parallel-perpendicular.html
http://www.youtube.com/watch?v=Rew54K6mYUo
http://www.regentsprep.org/Regents/math/ALGEBRA/AC3/Lparallel.htm
My link : http://animoto.com/play/v74LVRGRSVicGwYZeHWspQ