$cos(\pi /6 -cos^{-1}(-\sqrt{3}/2))$ is equal to :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → $-1/2$
$\cos(\pi /6 -\cos^{-1}(-\sqrt{3}/2))$
$=\cos(\pi /6 -\pi +\cos^{-1}\sqrt{3}/2)$
$=\cos(\pi /6 -\pi +\pi /6)$
$=\cos(\pi /3-\pi)=-1/2$