Trigonometry Examples

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

Step 1

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

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

Step 2

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

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

Step 3

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

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Step 3.1

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

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

Step 3.2

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

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

Step 3.3

Reorder the factors of $(1 - \cos (x)) (1 + \cos (x))$ .

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

Step 4

Combine the numerators over the common denominator.

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

Step 5

Simplify the numerator.

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Step 5.1

Apply the distributive property.

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

Step 5.2

Multiply $- 1$ by $1$ .

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

Step 5.3

Multiply $- \cos (x) (- \cos (x))$ .

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Step 5.3.1

Multiply $- 1$ by $- 1$ .

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

Step 5.3.2

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

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

Step 5.3.3

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

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

Step 5.3.4

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

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

Step 5.3.5

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

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

Step 5.3.6

Add $1$ and $1$ .

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

Step 5.4

Subtract $\cos (x)$ from $\cos (x)$ .

$\frac{1 + 0 + \cos^{2} (x)}{(1 + \cos (x)) (1 - \cos (x))}$

Step 5.5

Add $1$ and $0$ .

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