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Using L' Hospital's Rule evaluate : Li...

Using L' Hospital's Rule evaluate :
`Lim_(x to o)(1+sinx)^(cotx)`

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To evaluate the limit \( \lim_{x \to 0} (1 + \sin x)^{\cot x} \) using L'Hôpital's Rule, we can follow these steps: ### Step 1: Rewrite the Limit We start with the limit: \[ L = \lim_{x \to 0} (1 + \sin x)^{\cot x} \] This expression is of the form \( 1^\infty \) as \( x \to 0 \). To handle this, we can take the natural logarithm of \( L \): \[ \ln L = \lim_{x \to 0} \cot x \cdot \ln(1 + \sin x) \] ### Step 2: Analyze the Form As \( x \to 0 \), \( \cot x \) approaches \( \infty \) and \( \ln(1 + \sin x) \) approaches \( \ln(1 + 0) = 0 \). Thus, we have an indeterminate form \( \infty \cdot 0 \). We can rewrite this as: \[ \ln L = \lim_{x \to 0} \frac{\ln(1 + \sin x)}{\tan x} \] Now, this is in the form \( \frac{0}{0} \), which allows us to apply L'Hôpital's Rule. ### Step 3: Apply L'Hôpital's Rule We differentiate the numerator and the denominator: - The derivative of the numerator \( \ln(1 + \sin x) \) is: \[ \frac{d}{dx} \ln(1 + \sin x) = \frac{\cos x}{1 + \sin x} \] - The derivative of the denominator \( \tan x \) is: \[ \frac{d}{dx} \tan x = \sec^2 x \] Now we apply L'Hôpital's Rule: \[ \ln L = \lim_{x \to 0} \frac{\frac{\cos x}{1 + \sin x}}{\sec^2 x} = \lim_{x \to 0} \frac{\cos x \cdot \cos^2 x}{1 + \sin x} \] ### Step 4: Simplify the Expression This simplifies to: \[ \ln L = \lim_{x \to 0} \frac{\cos^3 x}{1 + \sin x} \] Now, substituting \( x = 0 \): \[ \ln L = \frac{\cos^3(0)}{1 + \sin(0)} = \frac{1^3}{1 + 0} = 1 \] ### Step 5: Exponentiate to Find L Since \( \ln L = 1 \), we exponentiate to find \( L \): \[ L = e^1 = e \] ### Final Answer Thus, the limit is: \[ \lim_{x \to 0} (1 + \sin x)^{\cot x} = e \]
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