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Find the direction cosines of the vector joining the points `A(1, 2, -3) and B(-1, -2, 1)` directed from `A` to `B`. |
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Answer» The given points are `A(1, 2, -3) and B(-1, -2, 1)`. Therefore, `" "vec(AB)=(-1-1)hati+(-2-2)hatj+{1-(-3)}hatk` `" "=-2hati-4hatj+4hatk` `therfore" "|vec(AB)|=sqrt((-2)^(2)+(-4)^(2) + 4^(2)) =sqrt(4+ 16 +16) ` `" "=sqrt(36) = 6` Hence, the direction cosines of `vec(AB)` are `" "(-(2)/(6), -(4)/(6), (4)/(6))=(-(1)/(3), -(2)/(3), (2)/(3))`. |
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