Precalculus Examples

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

Step 1

Simplify each term.

Tap for more steps...

Step 1.1

Since $\sin (- x)$ is an odd function, rewrite $\sin (- x)$ as $- \sin (x)$ .

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

Step 1.2

Since $\cos (- x)$ is an even function, rewrite $\cos (- x)$ as $\cos (x)$ .

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

Step 1.3

Simplify the numerator.

Tap for more steps...

Step 1.3.1

Since $\sin (- x)$ is an odd function, rewrite $\sin (- x)$ as $- \sin (x)$ .

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

Step 1.3.2

Multiply $- - \sin (x)$ .

Tap for more steps...

Step 1.3.2.1

Multiply $- 1$ by $- 1$ .

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

Step 1.3.2.2

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

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

Step 1.4

Since $\cos (- x)$ is an even function, rewrite $\cos (- x)$ as $\cos (x)$ .

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

Step 2

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

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

Step 3

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

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

Step 4

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

Tap for more steps...

Step 4.1

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

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

Step 4.2

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

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

Step 4.3

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

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

Step 5

Combine the numerators over the common denominator.

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

Step 6

Simplify the numerator.

Tap for more steps...

Step 6.1

Expand $(1 - \sin (x)) (1 - \cos (x))$ using the FOIL Method.

Tap for more steps...

Step 6.1.1

Apply the distributive property.

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

Step 6.1.2

Apply the distributive property.

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

Step 6.1.3

Apply the distributive property.

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

Step 6.2

Simplify each term.

Tap for more steps...

Step 6.2.1

Multiply $1$ by $1$ .

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

Step 6.2.2

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

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

Step 6.2.3

Multiply $- 1$ by $1$ .

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

Step 6.2.4

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

Tap for more steps...

Step 6.2.4.1

Multiply $- 1$ by $- 1$ .

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

Step 6.2.4.2

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

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

Step 6.3

Apply the distributive property.

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

Step 6.4

Multiply $- 1$ by $1$ .

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

Step 6.5

Expand $(- 1 - \sin (x)) (1 + \cos (x))$ using the FOIL Method.

Tap for more steps...

Step 6.5.1

Apply the distributive property.

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

Step 6.5.2

Apply the distributive property.

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

Step 6.5.3

Apply the distributive property.

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

Step 6.6

Simplify each term.

Tap for more steps...

Step 6.6.1

Multiply $- 1$ by $1$ .

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

Step 6.6.2

Rewrite $- 1 \cos (x)$ as $- \cos (x)$ .

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

Step 6.6.3

Multiply $- 1$ by $1$ .

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

Step 6.7

Subtract $1$ from $1$ .

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

Step 6.8

Subtract $\cos (x)$ from $0$ .

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

Step 6.9

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

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

Step 6.10

Subtract $\sin (x)$ from $- \sin (x)$ .

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

Step 6.11

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

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

Step 6.12

Subtract $2 \cos (x)$ from $0$ .

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

Step 6.13

Factor $- 2$ out of $- 2 \cos (x) - 2 \sin (x)$ .

Tap for more steps...

Step 6.13.1

Factor $- 2$ out of $- 2 \cos (x)$ .

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

Step 6.13.2

Factor $- 2$ out of $- 2 \sin (x)$ .

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

Step 6.13.3

Factor $- 2$ out of $- 2 (\cos (x)) - 2 (\sin (x))$ .

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

Step 7

Move the negative in front of the fraction.

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