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  1. Chapter 11 Class 12 Three Dimensional Geometry
  2. Serial order wise

Transcript

Misc 4 (Introduction) Find the equation of a line parallel to x-axis and passing through the origin.Direction cosines of a line making angle ๐›ผ with x -axis, ๐›ฝ with y โ€“ axis and ๐›พ with z โ€“ axis are l, m, n l = cos ๐›ผ , m = cos ๐›ฝ , n = cos ๐›พ x โ€“ axis makes an angle 0ยฐ with x โ€“ axis, 90ยฐ with y โ€“ axis & 90ยฐ with z โ€“ axis. So, ๐›ผ = 0ยฐ, ๐›ฝ = 90ยฐ, ๐›พ = 90ยฐ Direction cosines are l = cos 0ยฐ , m = cos 90ยฐ , n = cos 90ยฐ l = 1 , m = 0, n = 0 โˆด Direction cosines of x โ€“ axis are 1, 0, 0. Misc 4 Find the equation of a line parallel to x-axis and passing through the origin.Equation of a line passing through (x1, y1, z1) and parallel to a line with direction ratios a, b, c is (๐’™ โˆ’ ๐’™๐Ÿ)/๐’‚ = (๐’š โˆ’ ๐’š๐Ÿ)/๐’ƒ = (๐’› โˆ’ ๐’›๐Ÿ)/๐’„ Since line passes through origin ie. (0, 0, 0), x1 = 0, y1 = 0, z1 = 0 Since line is parallel to x โ€“ axis, ๐‘Ž = 1, b = 0, c = 0 Equation of line is (๐‘ฅ โˆ’ 0)/1 = (๐‘ฆ โˆ’ 0)/0 = (๐‘ง โˆ’ 0)/0 ๐’™/๐Ÿ = ๐’š/๐ŸŽ = ๐’›/๐ŸŽ

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.