MCQ
$2 \sin \left(12^{\circ}\right)-\sin \left(72^{\circ}\right)$ નું મુલ્ય ............ છે.
- A$\frac{\sqrt{5}(1-\sqrt{3})}{4}$
- B$\frac{1-\sqrt{5}}{8}$
- C$\frac{\sqrt{3}(1-\sqrt{5})}{2}$
- D$\frac{\sqrt{3}(1-\sqrt{5})}{4}$
$=\sin 12^{\circ}-2 \cos 42^{\circ} \sin 30^{\circ}$
$=\sin 12^{\circ}-\sin 48^{\circ}$
$=-2 \cos 30^{\circ} \sin 18^{\circ}$
$=-2 \times \frac{\sqrt{3}}{2} \times \frac{\sqrt{5}-1}{4}$
$=\frac{\sqrt{3}}{4}(1-\sqrt{5})$
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