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+1 vote
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in Limits by (49.0k points)
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limx→0 (cosec x - cot x)/x is

A. -1/2

B. 1

C. 1/2

D. -1

2 Answers

+2 votes
by (50.4k points)
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Best answer

Sin 2x = 2 Sinx Cosx

Hence Option (C) is the correct answer.

by (10 points)
+1
thanks so much and very good expalnation
+1 vote
by (17.0k points)

Given,

\(\lim\limits_{x\to 0} \frac{cosec x - cot x}x\)

\(= \lim\limits_{x\to 0} \cfrac{(\frac 1{\sin x})- \frac{\cos x}{\sin x}}x\)

\(= \lim\limits_{x\to 0} \frac{1 - \cos x}{x . \sin x}\)

\(= \lim\limits_{x\to 0} \cfrac{2\frac{\sin^2x}x}{x.2\frac{\sin x}2 \frac{\cos x}2}\)

\(= \lim\limits_{x\to 0} \cfrac{\frac {\tan x}2}x\)

\(= \lim\limits_{x\to 0}\cfrac{\frac{\tan x}2}{\frac x2}.\frac 12\)

\(= \frac 12\)     \(\left[\because \lim\limits_{\theta\to 0} \frac{\tan \theta}\theta = 1\right]\)

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