Let

-> -> -> ->

u = 3 i -2j + k

and

-> -> -> ->

v = 2i + j - k

-> ->

a)calculate the dot product of u and v

-> ->

a)calculate the cross product of u and v

-> ->

c)calculate 5 u - v

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- November 25th 2008, 07:26 AMFazvector2
Let

-> -> -> ->

u = 3 i -2j + k

and

-> -> -> ->

v = 2i + j - k

-> ->

a)calculate the dot product of u and v

-> ->

a)calculate the cross product of u and v

-> ->

c)calculate 5 u - v - November 25th 2008, 07:44 AMDavid24

hey mate,

In relation to (a), (b), for any two 3 Dimensional vectors of the form

v1 = a1*i + b1*j + c1*k, v2 = a2*i + b2*j + c2*k

Their Euclidean Inner or 'Dot' Product is calculated using either

(i) v1 . v2 = a1*a2 + b1*b2 + c1*c2

(ii) v1 . v2 = |v1|*|v2|*cos(y) where y is the angle between v1 and v2

Since the angle is unknown I would recommend using (i)

Their Cross Product is defined as,

v1 X v2 = det(A), where A is a 3x3 matrix where the first row of A = (i,j,k), the second row is v1 and the third is v2

For (c)

As before for a given three dimension vector of the form v1 (as defined previously)

Scalar Multiplication -

m*v1 = m(a1*i + b1*j + c1*k) = m*a1*i + m*b1*j + m*c*k

Addition

v1 + v2 = (a1 + a2)*i + (b1+b2)*j + (c1 + c2)*k

Hope this helps,

Let me know if you require any further assistance,

Regards,

David - November 25th 2008, 08:21 AMFazvector2
hi

i got these answer plse check for me.

a)6i-2j-k

b)

i j k 1st row

3 -2 1 second row

2 1 -1 3rd row in matrix form

c)17i-9j-4k

thks. - November 25th 2008, 08:38 AMSoroban
Hello, Faz!

These are straight forward . . . exactly**where**is your difficulty?

Quote:

Given: .

a) Find: .

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b) Find: .

Quote:

c) Find: .

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- November 25th 2008, 05:17 PMFazvectors
Thank you guys...u are the best....i understand it very clearly.