Posted by **koks** on Sunday, December 2, 2012 at 3:05am.

find the magnitude of vector by scalar and vector A= ? + 4j +4k B= ? + 2j + 3k if the angle between them 15 degrees.

- physics -
**bobpursley**, Sunday, December 2, 2012 at 10:36am
There is some algebra to this..

AdotB=MagA*MagB*costheta

ab+8+12=sqrt[(a^2+14+16)(b^2+4+9)]*cosTheta

which cant be solved, unless a,b are equal where a and b are the i components of each vector. Assuming them the same,

a^2+20=sqrt[(a^2+30)(a^2+13)] * cos15

now square both sides, find a

Vectors are A=ai+4j+4k and B=ai+2J+3k)

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