MCQ
$\sin 15^{\circ}+\cos 105^{\circ}=$
  • $0$
  • B
    $2 \sin 15^{\circ}$
  • C
    $\cos 15^{\circ}+\sin 15^{\circ}$
  • D
    $\sin 15^{\circ}-\cos 15^{\circ}$

Answer

Correct option: A.
$0$
(A)
$\sin 15^{\circ}+\cos 105^{\circ}$
$=\sin 15^{\circ}+\cos \left(90^{\circ}+15^{\circ}\right)$
$=\sin 15^{\circ}-\sin 15^{\circ}$
$\ldots\left[\because \cos \left(90^{\circ}+\theta\right)=-\sin \theta\right]$
= 0

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