1.

If |a|=10, |b|=2 and a.b=12, then value of |a xx b| is

Answer»

5
10
14
16

Solution :Given, `|a|=10, |b|=2` and `a.b =12`
`:' a.b =|a||b| cos THETA`
`implies 12=10xx2.cos theta`
`implies cos theta=3/5`
`:' axxb=|a||b| sin theta.HAT(N)`
`implies |axxb|=|a||b||sin theta|.|hat(n)|""[ :' |hat(n)|=1]`
`implies |axxb|=10.2.|sqrt(1-cos^(2) theta)|.1`
`=20.|sqrt(1-9//25)|`
`=20xxsqrt(|16/25|)=20xx4/5`
`implies |axxb|=16`


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