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Unit vector `hat(P)` and `hat(Q)` are inclined at an angle `theta`. Prove that `|hat(P)-hat(Q)|= 2 sin(theta//2)`.A. `(2 sin)(theta)/2`B. `(2 cos)(theta)/2`C. `(2 tan)(theta)/2`D. `tan theta` |
Answer» Correct Answer - A `|hat(A)-hat(B)|^(2)= (hat(A)-hat(B)).(hat(A)-hat(B))` `=hat(A).hat(A)-hat(A).hat(B)-hat(B).hat(A)+hat(B).hat(B)` `= 1-hat(A).hat(B)-hat(A).hat(B)+1` `=2-2 cos theta= 2(1-cos theta)` `=2((2sin)^(2)(theta)/2)= 4 (sin^(2))(theta)/2` `hat(A)-hat(B)| = (2sin^(2))(theta)/2` |
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