Question

Cos15° - Cos75°

Please answer this​

Answer 1

$\underline{\underline{\mathfrak{\Large{Solution : }}}} \\ \\ \\ \bf\: Cos15\degree - Cos75\degree \\ \\ \\ \sf\implies\: Cos15\degree - Cos (90\degree - 15\degree) \\ \\ \\ \sf\implies\: Cos15\degree - Sin15\degree \\ \\ \\ \sf\implies\dfrac {\sqrt {3} + 1}{2\sqrt {2 }} - \dfrac {\sqrt {3} - 1}{2\sqrt {2}} = \dfrac{\sqrt {3} + 1 - (\sqrt {3 } - 1)}{2\sqrt {2}}\\ \\ \\ \sf\implies\dfrac {\sqrt {3} + 1 - \sqrt {3} + 1}{2\sqrt {2}} =\bf \dfrac {1}{\sqrt {2}}$

Answer 2

$\huge\underline\mathfrak{Solutions :}$

cos15° - cos75°

cos 15° - cos( 90 -15°)

cos 15° - sin15°

$\frac{ \sqrt{3 + 1} }{2 \sqrt{2} } - \frac{ \sqrt{3 - 1} }{2 \sqrt{2} } \\ \\ = </p><p></p><p>\frac{ \sqrt{3 + 1 - ( \sqrt{3 - 1)} } }{2 \sqrt{2} } \\ \\ </p><p></p><p>\frac{ \sqrt{3 + 1 - \sqrt{3 + 1} } }{2 \sqrt{2} } = \frac{1}{ \sqrt{2} }$

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