Differentiation Question 120

Question: $ \frac{d}{dx}{{\cos }^{-1}}\sqrt{\cos x}= $

Options:

A) $ \frac{1}{2}\sqrt{1+\sec x} $

B) $ \sqrt{1+\sec x} $

C) $ -\frac{1}{2}\sqrt{1+\sec x} $

D) $ -\sqrt{1+\sec x} $

Show Answer

Answer:

Correct Answer: A

Solution:

$ \frac{d}{dx}{{\cos }^{-1}}\sqrt{\cos x}=\frac{\sin x}{2\sqrt{\cos x}\sqrt{1-\cos x}} $

$ =\frac{\sqrt{1-{{\cos }^{2}}x}}{2\sqrt{\cos x}\sqrt{1-\cos x}}=\frac{1}{2}\sqrt{\frac{1+\cos x}{\cos x}} $ .