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## #1 2006-03-07 17:33:44

ganesh
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### Vectors

V # 1

Show that the vetcors a = (2,3,1), b = (5,-2,-4), and c = (10,-13,19) are mutually perpendicular.

Character is who you are when no one is looking.

## #2 2006-05-15 17:29:59

luca-deltodesco
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### Re: Vectors

a dot b = cosine of angle between them, cosine of 90 degrees is 0, so if a dot b is 0, they are perpendicular

a dot b = 2*5 + 3*-2 + 1*-4 = 10-6-4 = 0, a,b are perpendicular
a dot c = 2*10 + 3*-13 + 1*19 = 20 - 39 + 19 = 0, a,c are perpendicular
b dot c = 5*10 + -2*-13 + -4*19 = 50 + 26 - 76 = 0, b,c, are perpendicular

Last edited by luca-deltodesco (2006-05-15 17:30:45)

The Beginning Of All Things To End.
The End Of All Things To Come.

## #3 2006-05-15 18:09:28

ganesh
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### Re: Vectors

Very well done, luca-deltodesco!

Character is who you are when no one is looking.

## #4 2007-06-10 00:31:28

angel_12
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### Re: Vectors

waise that was a bit easy one!

## #5 2007-11-07 08:16:27

mikau
Super Member

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### Re: Vectors

i'd like to demand lots of vector proof problems, please!

can't find enough of them.

A logarithm is just a misspelled algorithm.

## #6 2011-12-29 03:17:02

anonimnystefy
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### Re: Vectors

hi ganesh

only one problem??? o.O

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment