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Which one of the following vectors is a magnitude 6 and perpendicular to both `a=2hati+2hatj+hatk and b=hati-2hatj+2hatk`?A. `2hati-hatj-2hatk`B. `2(2hati-hatj+2hatk)`C. `3(2hati-hatj-2hatk)`D. `2(2hati-hatj-2hatk)` |
Answer» Correct Answer - D Now , `axxb=|{:(hat(i),hat(j),hat(k)),(2,2,1),(1,-2,2):}|=hat(i)(4+2)-hat(j)(4-1)+hat(k)(-4-2)` `6hat(i)-3hat(j)-6hat(k)` `|axxb|=sqrt(36+9+36)=sqrt(81)=9` `therefore` Requried vectors are `+-6|(axxb)/(|axxb||)|=+-(6)/(9)(6hat(i)-3hat(j)-6hat(k))=+-2(2hat(i)-hat(j)-2hat(k))` |
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