$ \cos ^{3}\left(\frac{\pi}{8}\right) \cdot \cos \left(\frac{3 \pi}{8}\right)+\sin ^{3}\left(\frac{\pi}{8}\right) \cdot \sin \left(\frac{3 \pi}{8}\right)$ ની કિમંત મેળવો.

  • [JEE MAIN 2020]
  • A

    $\frac{1}{4}$

  • B

    $\frac{1}{\sqrt{2}}$

  • C

    $\frac{1}{2\sqrt{2}}$

  • D

    $\frac{1}{2}$

Similar Questions

 $[1 - sin (3\pi - \alpha ) + cos (3\pi + \alpha )]$ $\left[ {1\,\, - \,\,\sin \,\left( {\frac{{3\,\pi }}{2}\,\, - \,\,\alpha } \right)\,\, + \,\,\cos \,\left( {\frac{{5\,\pi }}{2}\,\, - \,\,\alpha } \right)} \right]$ = 

$\sqrt 2 + \sqrt 3 + \sqrt 4 + \sqrt 6 = . . ..$

  • [IIT 1966]

$\tan 20^\circ \tan 40^\circ \tan 60^\circ \tan 80^\circ = $

  • [IIT 1974]

જો $2{\cos ^2}\theta - 2{\sin ^2}\theta = 1$,તો $\theta  =$ .....$^o$

જો $\cos A = \cos B\,\,\cos C$ અને $A + B + C = \pi ,$ તો $\cot \,B\,\cot \,C = . . . ..$