https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/v/perpendicular-lines-2 2021-03-12T17:07:31Z Writing equations of perpendicular lines Given line A and point P, Sal finds the equation of the line perpendicular to A that passes through P. Sal Khan video https://cdn.kastatic.org/googleusercontent/iqgHQBQH8RIda2Dk7Tlk8BGlj7D6QV7z2WlzkC3iej9kQYm0qjH-N4qMQlXVgn4RoQJwj3stj1evZruOswSsGi6i Writing equations of perpendicular lines Given line A and point P, Sal finds the equation of the line perpendicular to A that passes through P. https://cdn.kastatic.org/ka-youtube-converted/TsEhZRT16LU.mp4/TsEhZRT16LU.mp4 181 Equations of parallel & perpendicular lines https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/v/find-the-equation-of-a-line 2022-09-10T02:03:40.164764806Z Writing equations of perpendicular lines (example 2) Sal finds the equation of a line perpendicular to a line given in slope-intercept form that passes through a specific point. video https://cdn.kastatic.org/ka_thumbnails_cache/cd30e8e2-1efc-4bf4-8634-a65ae37fbd8d_1280_720_base.png Writing equations of perpendicular lines (example 2) Sal finds the equation of a line perpendicular to a line given in slope-intercept form that passes through a specific point. https://cdn.kastatic.org/ka-youtube-converted/8m8hFcFJ-JM.mp4/8m8hFcFJ-JM.mp4 105 Equations of parallel & perpendicular lines https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/e/writing-equations-for-parallel-or-perpendicular-lines 2026-03-19T10:07:17.424260476Z Write equations of parallel & perpendicular lines Write the equation for a line that is a parallel or perpendicular to a line given in slope-intercept form and goes through a specific point. . exercise https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/v/proving-that-parallel-lines-have-the-same-slope 2022-10-07T00:00:24.225559754Z Proof: parallel lines have the same slope Sal proves that parallel lines have the same slope using triangle similarity. video https://cdn.kastatic.org/ka_thumbnails_cache/7e99591f-b908-4ab3-aa98-39b92da11e67_1280_720_base.png Proof: parallel lines have the same slope Sal proves that parallel lines have the same slope using triangle similarity. https://cdn.kastatic.org/ka-youtube-converted/9ZYoIliBXYE.mp4/9ZYoIliBXYE.mp4 349 Equations of parallel & perpendicular lines https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/v/proof-that-perpendicular-lines-have-negative-reciprocal-slope 2023-05-12T21:01:01.897246564Z Proof: perpendicular lines have opposite reciprocal slopes To prove that perpendicular lines have opposite reciprocal slopes, draw the two lines and label key points. By identifying the two right triangles that are formed, one can use the definition of slope to calculate the slopes of the two lines. Finally, using the properties of similar right triangles, show that the two slopes are indeed opposite reciprocals of each other. video https://cdn.kastatic.org/ka_thumbnails_cache/2bc66806-665b-4fd9-b916-90c0d1722d9f_1280_720_base.png Proof: perpendicular lines have opposite reciprocal slopes To prove that perpendicular lines have opposite reciprocal slopes, draw the two lines and label key points. By identifying the two right triangles that are formed, one can use the definition of slope to calculate the slopes of the two lines. Finally, using the properties of similar right triangles, show that the two slopes are indeed opposite reciprocals of each other. https://cdn.kastatic.org/ka-youtube-converted/HyThzLRuqXo.mp4/HyThzLRuqXo.mp4 535 Equations of parallel & perpendicular lines https://www.khanacademy.org/math/geometry/hs-geo-analytic-geometry/hs-geo-parallel-perpendicular-eq/a/analytic-geometry-faq 2026-04-07T17:44:52.822958724Z Analytic geometry FAQ Frequently asked questions about analytic geometry article