JEE Math Practice Question
If $${a_r} = \cos {{2r\pi } \over 9} + i\sin {{2r\pi } \over 9}$$, r = 1, 2, 3, ....., i = $$\sqrt { - 1} $$, then the determinant $$\left| {\begin{matrix} {{a_1}} & {{a_2}} & {{a_3}} \\ {{a_4}} & {{a_5}} & {{a_6}} \\ {{a_7}} & {{a_8}} & {{a_9}} \\ \end{matrix} } \right|$$ is equal to :
- A.a2a6 $$-$$ a4a8
- B.a9
- C.a1a9 $$-$$ a3a7
- D.a5
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