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Question
Find the direction cosines of the line joining the points P(4,3,-5) and Q(-2,1,-8) .
Solution
P(4,3,-5) & Q(-2,1,-8)
equation of line
`(x-4)/(-2-4) = (y-3)/(1-3) = (z+5)/(-8-(-5)) = lambda`
`(x-4)/-6 = (y-3)/-2 = (z+5)/-3 = lambda`
`therefore "drs of line is" 6,2,3`
⇒ `dcs = 6/(sqrt(6^2+2^2+3^2)) , 2/(sqrt(6^2+2^2+3^2)) , 3/(sqrt(6^2+2^2+3^2))`
= `6/7 , 2/7 , 3/7`
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