यदि $\tan \theta = \frac{{\sin \alpha - \cos \alpha }}{{\sin \alpha + \cos \alpha }},$ तो $\sin \alpha + \cos \alpha $ व $\sin \alpha - \cos \alpha $ बराबर होंगे
$\sqrt 2 \cos \theta ,\,\,\sqrt 2 \sin \theta $
$\sqrt 2 \sin \theta ,\,\,\sqrt 2 \cos \theta $
$\sqrt 2 \sin \theta ,\,\,\sqrt 2 \sin \theta $
$\sqrt 2 \,\cos \theta ,\,\,\sqrt 2 \,\cos \theta $
$\cos \left(\frac{2 \pi}{7}\right)+\cos \left(\frac{4 \pi}{7}\right)+\cos \left(\frac{6 \pi}{7}\right)$ का मान बराबर होगा।
${\sin ^2}\frac{\pi }{8} + {\sin ^2}\frac{{3\pi }}{8} + {\sin ^2}\frac{{5\pi }}{8} + {\sin ^2}\frac{{7\pi }}{8} = $
$\frac{{\cos 12^\circ - \sin 12^\circ }}{{\cos 12^\circ + \sin 12^\circ }} + \frac{{\sin 147^\circ }}{{\cos 147^\circ }} = $
$2{\cos ^2}\theta - 2{\sin ^2}\theta = 1$, तो $\theta =$ ..........$^o$
यदि ${\cos ^6}\alpha + {\sin ^6}\alpha + K\,{\sin ^2}2\alpha = 1,$ हो तो $K $ का मान होगा