Cos

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[Nathi123]

A=[tex]\frac{cos25^ \circ cos35^\circ-sin25^ \circ sin35^\circ}{2sin30^ \circ cos 30^\circ}=\frac{cos(25^\circ+35^\circ)}{sin60^\circ} =\frac{cos60^\circ}{sin60^\circ} = cotg60^\circ =\frac{1}{\sqrt{3}}[/tex]