Calculus Examples

$f (x) = \ln (\tan (\frac{x}{2} + \frac{π}{4}))$

Step 1

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \ln (x)$ and $g (x) = \tan (\frac{x}{2} + \frac{π}{4})$ .

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Step 1.1

To apply the Chain Rule, set $u_{1}$ as $\tan (\frac{x}{2} + \frac{π}{4})$ .

$\frac{d}{d u_{1}} [\ln (u_{1})] \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 1.2

The derivative of $\ln (u_{1})$ with respect to $u_{1}$ is $\frac{1}{u_{1}}$ .

$\frac{1}{u_{1}} \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 1.3

Replace all occurrences of $u_{1}$ with $\tan (\frac{x}{2} + \frac{π}{4})$ .

$\frac{1}{\tan (\frac{x}{2} + \frac{π}{4})} \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 2

Rewrite $\tan (\frac{x}{2} + \frac{π}{4})$ in terms of sines and cosines.

$\frac{1}{\frac{\sin (\frac{x}{2} + \frac{π}{4})}{\cos (\frac{x}{2} + \frac{π}{4})}} \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 3

Multiply by the reciprocal of the fraction to divide by $\frac{\sin (\frac{x}{2} + \frac{π}{4})}{\cos (\frac{x}{2} + \frac{π}{4})}$ .

$\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 4

Convert from $\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})}$ to $\cot (\frac{x}{2} + \frac{π}{4})$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \frac{d}{d x} [\tan (\frac{x}{2} + \frac{π}{4})]$

Step 5

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \tan (x)$ and $g (x) = \frac{x}{2} + \frac{π}{4}$ .

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Step 5.1

To apply the Chain Rule, set $u_{2}$ as $\frac{x}{2} + \frac{π}{4}$ .

$\cot (\frac{x}{2} + \frac{π}{4}) (\frac{d}{d u_{2}} [\tan (u_{2})] \frac{d}{d x} [\frac{x}{2} + \frac{π}{4}])$

Step 5.2

The derivative of $\tan (u_{2})$ with respect to $u_{2}$ is $\sec^{2} (u_{2})$ .

$\cot (\frac{x}{2} + \frac{π}{4}) (\sec^{2} (u_{2}) \frac{d}{d x} [\frac{x}{2} + \frac{π}{4}])$

Step 5.3

Replace all occurrences of $u_{2}$ with $\frac{x}{2} + \frac{π}{4}$ .

$\cot (\frac{x}{2} + \frac{π}{4}) (\sec^{2} (\frac{x}{2} + \frac{π}{4}) \frac{d}{d x} [\frac{x}{2} + \frac{π}{4}])$

Step 6

Differentiate.

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Step 6.1

By the Sum Rule, the derivative of $\frac{x}{2} + \frac{π}{4}$ with respect to $x$ is $\frac{d}{d x} [\frac{x}{2}] + \frac{d}{d x} [\frac{π}{4}]$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) (\frac{d}{d x} [\frac{x}{2}] + \frac{d}{d x} [\frac{π}{4}])$

Step 6.2

Since $\frac{1}{2}$ is constant with respect to $x$ , the derivative of $\frac{x}{2}$ with respect to $x$ is $\frac{1}{2} \frac{d}{d x} [x]$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) (\frac{1}{2} \frac{d}{d x} [x] + \frac{d}{d x} [\frac{π}{4}])$

Step 6.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) (\frac{1}{2} \cdot 1 + \frac{d}{d x} [\frac{π}{4}])$

Step 6.4

Multiply $\frac{1}{2}$ by $1$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) (\frac{1}{2} + \frac{d}{d x} [\frac{π}{4}])$

Step 6.5

Since $\frac{π}{4}$ is constant with respect to $x$ , the derivative of $\frac{π}{4}$ with respect to $x$ is $0$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) (\frac{1}{2} + 0)$

Step 6.6

Combine fractions.

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Step 6.6.1

Add $\frac{1}{2}$ and $0$ .

$\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4}) \frac{1}{2}$

Step 6.6.2

Combine $\frac{1}{2}$ and $\cot (\frac{x}{2} + \frac{π}{4})$ .

$\frac{\cot (\frac{x}{2} + \frac{π}{4})}{2} \sec^{2} (\frac{x}{2} + \frac{π}{4})$

Step 6.6.3

Combine $\frac{\cot (\frac{x}{2} + \frac{π}{4})}{2}$ and $\sec^{2} (\frac{x}{2} + \frac{π}{4})$ .

$\frac{\cot (\frac{x}{2} + \frac{π}{4}) \sec^{2} (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7

Simplify.

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Step 7.1

Simplify the numerator.

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Step 7.1.1

Rewrite $\cot (\frac{x}{2} + \frac{π}{4})$ in terms of sines and cosines.

$\frac{\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} \sec^{2} (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.2

Rewrite $\sec (\frac{x}{2} + \frac{π}{4})$ in terms of sines and cosines.

$\frac{\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} {(\frac{1}{\cos (\frac{x}{2} + \frac{π}{4})})}^{2}}{2}$

Step 7.1.3

Apply the product rule to $\frac{1}{\cos (\frac{x}{2} + \frac{π}{4})}$ .

$\frac{\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} \cdot \frac{1^{2}}{\cos^{2} (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.4

Cancel the common factor of $\cos (\frac{x}{2} + \frac{π}{4})$ .

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Step 7.1.4.1

Factor $\cos (\frac{x}{2} + \frac{π}{4})$ out of $\cos^{2} (\frac{x}{2} + \frac{π}{4})$ .

$\frac{\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} \cdot \frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4}) \cos (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.4.2

Cancel the common factor.

$\frac{\frac{\cos (\frac{x}{2} + \frac{π}{4})}{\sin (\frac{x}{2} + \frac{π}{4})} \cdot \frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4}) \cos (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.4.3

Rewrite the expression.

$\frac{\frac{1}{\sin (\frac{x}{2} + \frac{π}{4})} \cdot \frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.5

Multiply $\frac{1}{\sin (\frac{x}{2} + \frac{π}{4})}$ by $\frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4})}$ .

$\frac{\frac{1^{2}}{\sin (\frac{x}{2} + \frac{π}{4}) \cos (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.6

Separate fractions.

$\frac{\frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4})} \cdot \frac{1}{\sin (\frac{x}{2} + \frac{π}{4})}}{2}$

Step 7.1.7

Convert from $\frac{1}{\sin (\frac{x}{2} + \frac{π}{4})}$ to $\csc (\frac{x}{2} + \frac{π}{4})$ .

$\frac{\frac{1^{2}}{\cos (\frac{x}{2} + \frac{π}{4})} \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.8

Separate fractions.

$\frac{\frac{1^{2}}{1} \cdot \frac{1}{\cos (\frac{x}{2} + \frac{π}{4})} \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.9

Convert from $\frac{1}{\cos (\frac{x}{2} + \frac{π}{4})}$ to $\sec (\frac{x}{2} + \frac{π}{4})$ .

$\frac{\frac{1^{2}}{1} \sec (\frac{x}{2} + \frac{π}{4}) \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.10

Divide $1^{2}$ by $1$ .

$\frac{1^{2} \sec (\frac{x}{2} + \frac{π}{4}) \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.11

One to any power is one.

$\frac{1 \sec (\frac{x}{2} + \frac{π}{4}) \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.1.12

Multiply $\sec (\frac{x}{2} + \frac{π}{4})$ by $1$ .

$\frac{\sec (\frac{x}{2} + \frac{π}{4}) \csc (\frac{x}{2} + \frac{π}{4})}{2}$

Step 7.2

Reorder terms.

$\frac{\csc (\frac{x}{2} + \frac{π}{4}) \sec (\frac{x}{2} + \frac{π}{4})}{2}$