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#1 2006-03-06 18:33:44
- Jai Ganesh
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- Registered: 2005-06-28
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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.
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
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#2 2006-05-14 19:29:59
- luca-deltodesco
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- Registered: 2006-05-05
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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 (2006-05-14 19:30:45)
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#3 2006-05-14 20:09:28
- Jai Ganesh
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Re: Vectors
Very well done, luca-deltodesco!
It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.
Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.
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#4 2007-06-09 02:31:28
- angel_12
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- Registered: 2007-06-07
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Re: Vectors
answer is already given...
waise that was a bit easy one!
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#5 2007-11-06 09:16:27
- mikau
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- Registered: 2005-08-22
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Re: Vectors
i'd like to demand lots of vector proof problems, please! 
can't find enough of them.
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#6 2011-12-28 04:17:02
- anonimnystefy
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Re: Vectors
hi ganesh
only one problem??? o.O
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