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Dot products of a vector with vectors ` hat i- hat j+ hat k , 2 hat i+ hat j-3 hat k a n d hat i+ hat j+ hat k`are respectively 4, 0 and 2. Find the vector. |
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Answer» Let the required vector be `(x hat(i)+y hat(j)+z hat(k))`. Then, `(x hat(i)+y hat(j)+z hat(k)). (hat(i)-hat(j)+hat(k))=4 implies x-y+z=4` ...(i) `(x hat(i)+y hat(j)+z hat(k)). (2hat(i)+hat(j)-3hat(k))=0implies 2x+y-3z=0`. ...(ii) `(x hat(i)+ y hat(j)+ z hat(k)).(hat(i)+hat(j)+hat(k))=2implies x+y+z=2` ...(iii) On subtracting (i) from (iii) we get `2y=-2 implies y=-1`. On adding (i) and (ii), we get `3x-2z=4` ...(iv) On adding (i) and (iii), we get `2x+2z=6` ...(v) On solving (iv) and (v), we get `x=2` and `z=1`. `:. x=2, y=-1` and `z=1` Hence, the required vector is `(2hat(i)-hat(j)+hat(k))`. |
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