Slide2.JPG

Slide3.JPG

Subscribe to our Youtube Channel - https://you.tube/teachoo

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

Transcript

Example 2 If a line has direction ratios 2, โ€“ 1, โ€“ 2, determine its direction cosines.If direction ratios of a line are a, b, c direction cosines are ๐‘Ž/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) , ๐‘/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) , ๐‘/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) Given, Direction ratios = 2, โˆ’1, โˆ’2 โˆด ๐‘Ž = 2, b = โˆ’1, c = โˆ’2 Also, โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) = โˆš(22 + (โˆ’1)2 + (โˆ’2)2) = โˆš(4 + 1 + 4) = โˆš9 = 3 Direction cosines = ๐‘Ž/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) , ๐‘/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) , ๐‘/โˆš(๐‘Ž^2 + ๐‘^2 + ๐‘^2 ) = ๐Ÿ/๐Ÿ‘ , (โˆ’๐Ÿ)/๐Ÿ‘ , (โˆ’๐Ÿ)/๐Ÿ‘

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
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.