Trigonometry Examples

$\frac{\cos (x)}{1 - \tan (x)} + \frac{\sin (x)}{1 - \cot (x)}$

Step 1

Simplify each term.

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Step 1.1

Rewrite $\tan (x)$ in terms of sines and cosines.

$\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}} + \frac{\sin (x)}{1 - \cot (x)}$

Step 1.2

Rewrite $\cot (x)$ in terms of sines and cosines.

$\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}} + \frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}}$

Step 2

To write $\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}}$ as a fraction with a common denominator, multiply by $\frac{1 - \frac{\cos (x)}{\sin (x)}}{1 - \frac{\cos (x)}{\sin (x)}}$ .

$\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}} \cdot \frac{1 - \frac{\cos (x)}{\sin (x)}}{1 - \frac{\cos (x)}{\sin (x)}} + \frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}}$

Step 3

To write $\frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}}$ as a fraction with a common denominator, multiply by $\frac{1 - \frac{\sin (x)}{\cos (x)}}{1 - \frac{\sin (x)}{\cos (x)}}$ .

$\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}} \cdot \frac{1 - \frac{\cos (x)}{\sin (x)}}{1 - \frac{\cos (x)}{\sin (x)}} + \frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}} \cdot \frac{1 - \frac{\sin (x)}{\cos (x)}}{1 - \frac{\sin (x)}{\cos (x)}}$

Step 4

Write each expression with a common denominator of $(1 - \frac{\sin (x)}{\cos (x)}) (1 - \frac{\cos (x)}{\sin (x)})$ , by multiplying each by an appropriate factor of $1$ .

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Step 4.1

Multiply $\frac{\cos (x)}{1 - \frac{\sin (x)}{\cos (x)}}$ by $\frac{1 - \frac{\cos (x)}{\sin (x)}}{1 - \frac{\cos (x)}{\sin (x)}}$ .

$\frac{\cos (x) (1 - \frac{\cos (x)}{\sin (x)})}{(1 - \frac{\sin (x)}{\cos (x)}) (1 - \frac{\cos (x)}{\sin (x)})} + \frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}} \cdot \frac{1 - \frac{\sin (x)}{\cos (x)}}{1 - \frac{\sin (x)}{\cos (x)}}$

Step 4.2

Multiply $\frac{\sin (x)}{1 - \frac{\cos (x)}{\sin (x)}}$ by $\frac{1 - \frac{\sin (x)}{\cos (x)}}{1 - \frac{\sin (x)}{\cos (x)}}$ .

$\frac{\cos (x) (1 - \frac{\cos (x)}{\sin (x)})}{(1 - \frac{\sin (x)}{\cos (x)}) (1 - \frac{\cos (x)}{\sin (x)})} + \frac{\sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 4.3

Reorder the factors of $(1 - \frac{\sin (x)}{\cos (x)}) (1 - \frac{\cos (x)}{\sin (x)})$ .

$\frac{\cos (x) (1 - \frac{\cos (x)}{\sin (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})} + \frac{\sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 5

Combine the numerators over the common denominator.

$\frac{\cos (x) (1 - \frac{\cos (x)}{\sin (x)}) + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6

Simplify the numerator.

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Step 6.1

Apply the distributive property.

$\frac{\cos (x) \cdot 1 + \cos (x) (- \frac{\cos (x)}{\sin (x)}) + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.2

Multiply $\cos (x)$ by $1$ .

$\frac{\cos (x) + \cos (x) (- \frac{\cos (x)}{\sin (x)}) + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.3

Rewrite using the commutative property of multiplication.

$\frac{\cos (x) - \cos (x) \frac{\cos (x)}{\sin (x)} + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.4

Multiply $- \cos (x) \frac{\cos (x)}{\sin (x)}$ .

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Step 6.4.1

Combine $\frac{\cos (x)}{\sin (x)}$ and $\cos (x)$ .

$\frac{\cos (x) - \frac{\cos (x) \cos (x)}{\sin (x)} + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.4.2

Raise $\cos (x)$ to the power of $1$ .

$\frac{\cos (x) - \frac{\cos^{1} (x) \cos (x)}{\sin (x)} + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.4.3

Raise $\cos (x)$ to the power of $1$ .

$\frac{\cos (x) - \frac{\cos^{1} (x) \cos^{1} (x)}{\sin (x)} + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.4.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{\cos (x) - \frac{{\cos (x)}^{1 + 1}}{\sin (x)} + \sin (x) (1 - \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 6.4.5

Add $1$ and $1$ .

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

Step 6.5

Apply the distributive property.

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

Step 6.6

Multiply $\sin (x)$ by $1$ .

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

Step 6.7

Rewrite using the commutative property of multiplication.

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

Step 6.8

Multiply $- \sin (x) \frac{\sin (x)}{\cos (x)}$ .

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Step 6.8.1

Combine $\frac{\sin (x)}{\cos (x)}$ and $\sin (x)$ .

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

Step 6.8.2

Raise $\sin (x)$ to the power of $1$ .

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

Step 6.8.3

Raise $\sin (x)$ to the power of $1$ .

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

Step 6.8.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

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

Step 6.8.5

Add $1$ and $1$ .

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

Step 7

Simplify the numerator.

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Step 7.1

Factor $\cos (x)$ out of $\cos^{2} (x)$ .

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

Step 7.2

Separate fractions.

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

Step 7.3

Convert from $\frac{\cos (x)}{\sin (x)}$ to $\cot (x)$ .

$\frac{\cos (x) - (\frac{\cos (x)}{1} \cot (x)) + \sin (x) - \frac{\sin^{2} (x)}{\cos (x)}}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 7.4

Divide $\cos (x)$ by $1$ .

$\frac{\cos (x) - (\cos (x) \cot (x)) + \sin (x) - \frac{\sin^{2} (x)}{\cos (x)}}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 7.5

Factor $\sin (x)$ out of $\sin^{2} (x)$ .

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - \frac{\sin (x) \sin (x)}{\cos (x)}}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 7.6

Separate fractions.

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - (\frac{\sin (x)}{1} \cdot \frac{\sin (x)}{\cos (x)})}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 7.7

Convert from $\frac{\sin (x)}{\cos (x)}$ to $\tan (x)$ .

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - (\frac{\sin (x)}{1} \tan (x))}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 7.8

Divide $\sin (x)$ by $1$ .

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - \sin (x) \tan (x)}{(1 - \frac{\cos (x)}{\sin (x)}) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 8

Simplify the denominator.

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Step 8.1

Convert from $\frac{\cos (x)}{\sin (x)}$ to $\cot (x)$ .

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - \sin (x) \tan (x)}{(1 - \cot (x)) (1 - \frac{\sin (x)}{\cos (x)})}$

Step 8.2

Convert from $\frac{\sin (x)}{\cos (x)}$ to $\tan (x)$ .

$\frac{\cos (x) - \cos (x) \cot (x) + \sin (x) - \sin (x) \tan (x)}{(1 - \cot (x)) (1 - \tan (x))}$