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If the sum of two unit vectors is a unit vector,then find the magnitude of their differences.A. `sqrt(2)`B. `sqer(3)`C. `1//sqer(2)`D. `sqrt(5)` |
Answer» Correct Answer - B Let `hat(n)_(1)` and `hat(n)_(2)` be the two unit vector, then the sum is `vec(n)_(s)= hat(n)_(1)+hat(n)_(2)` or `n_(s)^(2)= n_(1)^(2)+n_(2)^(2)+2n_(1)n_(2) cos theta` `1+1+2 cos theta` Since it is given that `n_(s)` is also a unit vector, therefore `1= 1+1+2 cos theta implies cos theta= -1/2 :. theta= 120^(@)` Now the difference Vector is `hat(n)_(d)=hat(n)_(1)-hat(n)_(2)` or `n_(d)^(2)= n_(1)^(2)+n_(2)^(2)-2n_(1)n_(2) cos theta = 1+1-2 cos(120^(@))` `:. n_(d)^(2)= 2-2(-1//2)= 2+1= 3 impliesn_(d)= sqrt(3)` |
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