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9 Apr 2008 14:18:48 IST

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find out the angle between vectors A=3i+2j and B=2i+j

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find out the angle between vectors A=3i+2j and B=2i+j

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Akhil

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Joined: 17 Jan 2008

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9 Apr 2008 14:20:29 IST

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http://www.goiit.com/posts/list/vectors-find-the-angle-between-vectors-a-3i-2j-and-b-2i-j-52091.htm

C!-!!NMAY

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9 Apr 2008 16:18:12 IST

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A.B=8(dot product)

IAI=root13
and IBI=root5

then A.B=IAIIBIcostheta
so costheta=A.B/IAIIBI= 8/ROOT65

AND THETA =COS-18/ROOT65

edison

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Joined: 19 Oct 2006

Posts: 7537

9 Apr 2008 20:35:28 IST

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A=3i+2j

and B=2i+j

So A.B = AB cos

or (3i+2j).(2i+j) =

(9 + 4)

(4 + 1) cos

or 3*2 + 2*1 =

(9 + 4)

(4 + 1) cos

(13*5) cos

= 8

or cos

= 8/

= cos^-1 8/

65 is the angle between the two vectors.

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