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Last updated at Feb. 1, 2020 by Teachoo
Transcript
Ex 11.1, 1 If a line makes angles 90ยฐ, 135ยฐ, 45ยฐ with the x, y and z โ axes respectively, find its direction cosines. Direction cosines of a line making angle ๐ผ with x โ axis, ๐ฝ with y โ axis and ๐พ with z โ axis are l, m, n l = cos ๐ผ, m = cos ๐ฝ, n = cos ๐พ Here, ๐ผ = 90ยฐ, ๐ฝ = 135ยฐ, ๐พ = 45ยฐ, So, direction cosines are l = cos 90ยฐ = 0 ๐ = cosโก135ยฐ = cos(180 โ 45ยฐ) = โcos 45ยฐ = (โ1)/โ2 ๐ = cos 45ยฐ = 1/โ2 Therefore, required direction cosines are 0, ( โ๐)/โ๐ , ๐/โ๐ .
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