1.

The area of the parallelogram whose adjacent sides are `hati-3hatj+hatk and hati+hatj+hatk` isA. `4sqrt2`B. `-4sqrt2`C. `4sqrt3`D. None of these

Answer» Correct Answer - B
Let , `a=hat(i)-3hat(j)+hat(k) and b=hat(i)+hat(j)+hat(k)`
`therefore` Area of parallelogram having adjacent sides, a and b is
`|a xxb|=|{:(hat(i),hat(j),hat(k)),(1,-3,1),(1,1,1):}|`
`=|hat(i)(-3-1)-hat(j)(1-1)+hat(k)(1+3)|`
`=|-4hat(i)+4hat(k)=sqrt((-4)^2+4^2)=sqrt(16+16)`
`=sqrt(32)=4sqrt(2)` sq units.


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