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Trigonometrical Equations
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સમીકરણ $\frac{{\left (sin 36^o + cos 36^o - \sqrt 2 sin 27^o)( {\sin {{36}^0} + \cos {{36}^0} - \sqrt 2 \sin {{27}^0}} \right)}}{{2\sin {{54}^0}}}$ ની કિમત ......... કરતાં ઓછી છે
A
${\cos {{36}^o}}$
B
$\cos 67\frac{{{1^o}}}{2}$
C
$\cos {9^o}$
D
$\cos {72^0}$
Solution
$\frac{{{{(\sin 36 + \cos 36)}^2} – 2{{\sin }^2}{{27}^\circ }}}{{2\sin {{54}^\circ }}}$
$ = \frac{{\cos {{54}^\circ } + \cos {{18}^\circ }}}{{2\sin {{54}^\circ }}} = \frac{{2\cos {{36}^\circ }\cos {{18}^\circ }}}{{2\cos {{36}^\circ }}}$
${=\cos 18^{\circ}<\cos 9^{\circ}}$
Standard 11
Mathematics
