A line passes through the points A(-2,4,-5) and B(1,2,3). Find the direction cosines of AB . The answer given in the book is:3/?77 ,(-2)/?77 ,8/?77

Asked by Manoj | 1st Jun, 2013, 05:41: PM

Expert Answer:

direction cosines = [x2-x1/(sqrt(x1-x2)^2 + (y1-y2)^2 +(z1-z2)^2), y2-y1/(sqrt(x1-x2)^2 + (y1-y2)^2 +(z1-z2)^2), z2-z1/(sqrt(x1-x2)^2 + (y1-y2)^2 +(z1-z2)^2)]
Hence direction cosines = [3/sqrt(77), -2/sqrt(77), 8/(sqrt(77)]

Answered by  | 2nd Jun, 2013, 05:24: AM

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