Question
find the direction cosines of the vector joining the two points (4,2,2,) & (7,6,14)
(this is new to me, used to think it was just one point not two.)
(this is new to me, used to think it was just one point not two.)
Answers
Damon
change in x = 7 - 4 = 3
change in y = 6 - 2 = 4
change i z = 14 - 2 = 12
so V = 3 i + 4 j + 12 k is in the direction
magnitude:
sqrt (9+16+144) = 13
dot product with unit x vector for example
V dot 1 i = 13 * 1 * cos angle
so
cos angle = 3/13
then y axis
cos angle = 4/13
and x
cos angle = 12/13
change in y = 6 - 2 = 4
change i z = 14 - 2 = 12
so V = 3 i + 4 j + 12 k is in the direction
magnitude:
sqrt (9+16+144) = 13
dot product with unit x vector for example
V dot 1 i = 13 * 1 * cos angle
so
cos angle = 3/13
then y axis
cos angle = 4/13
and x
cos angle = 12/13
bamaiyi
in the text book, the answer is -2i -7j -18k . could it be a mistake has being made? i mean your result or the one from the text
Idowu Temitope
I thinks the one on the textbook is correct but why are you doing change in x,y&z