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D is midpoint of BC in Delta ABC such th...

D is midpoint of BC in `Delta ABC` such that AD and AC are perpendicular, Show that `Cos A Cos C = (2 (c^2-a^2))/(3ac)`

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The correct Answer is:
From Eqs. (i) and(ii) ,`cos A. cos C=(2 (c^(2) -a^(2))/(3ac))`
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