InterviewSolution
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InterviewSolution
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Let ` vec a=2 hat i- hat j+ hat k , vec b= hat i+2 hat j= hat ka n d vec c= hat i+ hat j-2 hat k`be three vectors. A vector in the plane of ` vec ba n d vec c`, whose projection on ` vec a`is of magnitude `sqrt(2//3)`, is`2 hat i+3 hat j-3 hat k`b. `2 hat i-3 hat j+3 hat k`c. `-2 hat i- hat j+5 hat k`d. `2 hat i+ hat j+5 hat k`A. `2hat(i)+3hat(j)-3hat(k)`B. `2hat(i)+3hat(j)+3hat(k)`C. `2hat(i)-5hat(j)+5hat(k)`D. `2hat(i)+hat(j)+5hat(k)` |
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Answer» Correct Answer - A Any vector I the place of b and c is `r=mb+c(m+1)hati+(2m+1)hati+(-m-2)hatk` Projection of r on a `=(r*a)/(|a|)=|sqrt(2/3)|` `:." "(2(m+1)-(2m+1)+(-m-2))/(sqrt6)=+-sqrt(2/3)` `rArr" "-m-2+-2rArrm=-3"and"1` Hence, `r=-2hati-5hatj+hatk" and "r=2hati+3hatj-3hatk` |
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