Differentiation Question 178

Question: The value of $ \underset{x\to 0}{\mathop{\lim }}{\log _{e}}{{(sinx)}^{\tan x}} $ is

Options:

A) 1

B) -1

C) 0

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

[c] $ \underset{x\to 0}{\mathop{\lim }}{\log _{e}}{{(sinx)}^{\tan x}}=\underset{x\to 0}{\mathop{\lim }}\tan x.{\log _{e}}\sin x $

$ (0\cdot \infty form) $

$ \underset{x\to 0}{\mathop{\lim }}\frac{{\log _{e}}\sin x}{\cot x}( \frac{\infty }{\infty }form ) $

$ =\underset{x\to 0}{\mathop{\lim }}\frac{\cot x}{-\cos ec^{2}x} $ [Using L-Hospital’s rule] $ =\underset{x\to 0}{\mathop{\lim }}(-cosx.sinx)=0. $