Trigonometry Examples

$\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} = \frac{1}{1 - \sec (x)}$

Step 1

Subtract $\frac{1}{1 - \sec (x)}$ from both sides of the equation.

$\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2

Simplify $\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}$ .

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Step 2.1

Factor $1$ out of $\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}$ .

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Step 2.1.1

Factor $1$ out of $\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3}$ .

$1 \frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2.1.2

Factor $1$ out of $- \frac{1}{1 - \sec (x)}$ .

$1 \frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} + 1 (- \frac{1}{1 - \sec (x)}) = 0$

Step 2.1.3

Factor $1$ out of $1 \frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} + 1 (- \frac{1}{1 - \sec (x)})$ .

$1 (\frac{\sin^{2} (x) + 2 \cos (x) - 1}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.2

Move $- 1$ .

$1 (\frac{\sin^{2} (x) - 1 + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.3

Reorder $\sin^{2} (x)$ and $- 1$ .

$1 (\frac{- 1 + \sin^{2} (x) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.4

Rewrite $- 1$ as $- 1 (1)$ .

$1 (\frac{- 1 (1) + \sin^{2} (x) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.5

Factor $- 1$ out of $\sin^{2} (x)$ .

$1 (\frac{- 1 (1) - 1 (- \sin^{2} (x)) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.6

Factor $- 1$ out of $- 1 (1) - 1 (- \sin^{2} (x))$ .

$1 (\frac{- 1 (1 - \sin^{2} (x)) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.7

Rewrite $- 1 (1 - \sin^{2} (x))$ as $- (1 - \sin^{2} (x))$ .

$1 (\frac{- (1 - \sin^{2} (x)) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.8

Apply pythagorean identity.

$1 (\frac{- \cos^{2} (x) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}) = 0$

Step 2.9

Multiply $\frac{- \cos^{2} (x) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)}$ by $1$ .

$\frac{- \cos^{2} (x) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2.10

Simplify each term.

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Step 2.10.1

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

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Step 2.10.1.1

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

$\frac{\cos (x) (- \cos (x)) + 2 \cos (x)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2.10.1.2

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

$\frac{\cos (x) (- \cos (x)) + \cos (x) \cdot 2}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2.10.1.3

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

$\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \sec (x)} = 0$

Step 2.10.2

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

$\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3} - \frac{1}{1 - \frac{1}{\cos (x)}} = 0$

Step 2.11

To write $\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3}$ as a fraction with a common denominator, multiply by $\frac{1 - \frac{1}{\cos (x)}}{1 - \frac{1}{\cos (x)}}$ .

$\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3} \cdot \frac{1 - \frac{1}{\cos (x)}}{1 - \frac{1}{\cos (x)}} - \frac{1}{1 - \frac{1}{\cos (x)}} = 0$

Step 2.12

To write $- \frac{1}{1 - \frac{1}{\cos (x)}}$ as a fraction with a common denominator, multiply by $\frac{\sin^{2} (x) + 3 \cos (x) - 3}{\sin^{2} (x) + 3 \cos (x) - 3}$ .

$\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3} \cdot \frac{1 - \frac{1}{\cos (x)}}{1 - \frac{1}{\cos (x)}} - \frac{1}{1 - \frac{1}{\cos (x)}} \cdot \frac{\sin^{2} (x) + 3 \cos (x) - 3}{\sin^{2} (x) + 3 \cos (x) - 3} = 0$

Step 2.13

Write each expression with a common denominator of $(\sin^{2} (x) + 3 \cos (x) - 3) (1 - \frac{1}{\cos (x)})$ , by multiplying each by an appropriate factor of $1$ .

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Step 2.13.1

Multiply $\frac{\cos (x) (- \cos (x) + 2)}{\sin^{2} (x) + 3 \cos (x) - 3}$ by $\frac{1 - \frac{1}{\cos (x)}}{1 - \frac{1}{\cos (x)}}$ .

$\frac{\cos (x) (- \cos (x) + 2) (1 - \frac{1}{\cos (x)})}{(\sin^{2} (x) + 3 \cos (x) - 3) (1 - \frac{1}{\cos (x)})} - \frac{1}{1 - \frac{1}{\cos (x)}} \cdot \frac{\sin^{2} (x) + 3 \cos (x) - 3}{\sin^{2} (x) + 3 \cos (x) - 3} = 0$

Step 2.13.2

Multiply $\frac{1}{1 - \frac{1}{\cos (x)}}$ by $\frac{\sin^{2} (x) + 3 \cos (x) - 3}{\sin^{2} (x) + 3 \cos (x) - 3}$ .

$\frac{\cos (x) (- \cos (x) + 2) (1 - \frac{1}{\cos (x)})}{(\sin^{2} (x) + 3 \cos (x) - 3) (1 - \frac{1}{\cos (x)})} - \frac{\sin^{2} (x) + 3 \cos (x) - 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.13.3

Reorder the factors of $(\sin^{2} (x) + 3 \cos (x) - 3) (1 - \frac{1}{\cos (x)})$ .

$\frac{\cos (x) (- \cos (x) + 2) (1 - \frac{1}{\cos (x)})}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} - \frac{\sin^{2} (x) + 3 \cos (x) - 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.14

Combine the numerators over the common denominator.

$\frac{\cos (x) (- \cos (x) + 2) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15

Simplify the numerator.

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Step 2.15.1

Apply the distributive property.

$\frac{(\cos (x) (- \cos (x)) + \cos (x) \cdot 2) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.2

Rewrite using the commutative property of multiplication.

$\frac{(- \cos (x) \cos (x) + \cos (x) \cdot 2) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.3

Move $2$ to the left of $\cos (x)$ .

$\frac{(- \cos (x) \cos (x) + 2 \cdot \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.4

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

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Step 2.15.4.1

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

$\frac{(- (\cos^{1} (x) \cos (x)) + 2 \cdot \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.4.2

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

$\frac{(- (\cos^{1} (x) \cos^{1} (x)) + 2 \cdot \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.4.3

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

$\frac{(- {\cos (x)}^{1 + 1} + 2 \cdot \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.4.4

Add $1$ and $1$ .

$\frac{(- \cos^{2} (x) + 2 \cdot \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

$\frac{(- \cos^{2} (x) + 2 \cos (x)) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.5

Expand $(- \cos^{2} (x) + 2 \cos (x)) (1 - \frac{1}{\cos (x)})$ using the FOIL Method.

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Step 2.15.5.1

Apply the distributive property.

$\frac{- \cos^{2} (x) (1 - \frac{1}{\cos (x)}) + 2 \cos (x) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.5.2

Apply the distributive property.

$\frac{- \cos^{2} (x) \cdot 1 - \cos^{2} (x) (- \frac{1}{\cos (x)}) + 2 \cos (x) (1 - \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.5.3

Apply the distributive property.

$\frac{- \cos^{2} (x) \cdot 1 - \cos^{2} (x) (- \frac{1}{\cos (x)}) + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6

Simplify and combine like terms.

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Step 2.15.6.1

Simplify each term.

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Step 2.15.6.1.1

Multiply $- 1$ by $1$ .

$\frac{- \cos^{2} (x) - \cos^{2} (x) (- \frac{1}{\cos (x)}) + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.2

Cancel the common factor of $\cos (x)$ .

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Step 2.15.6.1.2.1

Move the leading negative in $- \frac{1}{\cos (x)}$ into the numerator.

$\frac{- \cos^{2} (x) - \cos^{2} (x) \frac{- 1}{\cos (x)} + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.2.2

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

$\frac{- \cos^{2} (x) + \cos (x) (- \cos (x)) \frac{- 1}{\cos (x)} + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.2.3

Cancel the common factor.

Step 2.15.6.1.2.4

Rewrite the expression.

$\frac{- \cos^{2} (x) - \cos (x) \cdot - 1 + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.3

Multiply $- 1$ by $- 1$ .

$\frac{- \cos^{2} (x) + 1 \cos (x) + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.4

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

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) \cdot 1 + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.5

Multiply $2$ by $1$ .

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) + 2 \cos (x) (- \frac{1}{\cos (x)}) - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.6

Cancel the common factor of $\cos (x)$ .

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Step 2.15.6.1.6.1

Move the leading negative in $- \frac{1}{\cos (x)}$ into the numerator.

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) + 2 \cos (x) \frac{- 1}{\cos (x)} - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.6.2

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

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) + \cos (x) \cdot 2 \frac{- 1}{\cos (x)} - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.6.3

Cancel the common factor.

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) + \cos (x) \cdot 2 \frac{- 1}{\cos (x)} - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.6.4

Rewrite the expression.

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) + 2 \cdot - 1 - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.1.7

Multiply $2$ by $- 1$ .

$\frac{- \cos^{2} (x) + \cos (x) + 2 \cos (x) - 2 - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.6.2

Add $\cos (x)$ and $2 \cos (x)$ .

$\frac{- \cos^{2} (x) + 3 \cos (x) - 2 - (\sin^{2} (x) + 3 \cos (x) - 3)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.7

Apply the distributive property.

$\frac{- \cos^{2} (x) + 3 \cos (x) - 2 - \sin^{2} (x) - (3 \cos (x)) - - 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.8

Simplify.

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Step 2.15.8.1

Multiply $3$ by $- 1$ .

$\frac{- \cos^{2} (x) + 3 \cos (x) - 2 - \sin^{2} (x) - 3 \cos (x) - - 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.8.2

Multiply $- 1$ by $- 3$ .

$\frac{- \cos^{2} (x) + 3 \cos (x) - 2 - \sin^{2} (x) - 3 \cos (x) + 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.9

Subtract $3 \cos (x)$ from $3 \cos (x)$ .

$\frac{- \cos^{2} (x) + 0 - 2 - \sin^{2} (x) + 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.10

Add $- \cos^{2} (x)$ and $0$ .

$\frac{- \cos^{2} (x) - 2 - \sin^{2} (x) + 3}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.11

Add $- 2$ and $3$ .

$\frac{- \cos^{2} (x) + 1 - \sin^{2} (x)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.12

Reorder $- \cos^{2} (x)$ and $1$ .

$\frac{1 - \cos^{2} (x) - \sin^{2} (x)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.13

Apply pythagorean identity.

$\frac{\sin^{2} (x) - \sin^{2} (x)}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.15.14

Subtract $\sin^{2} (x)$ from $\sin^{2} (x)$ .

$\frac{0}{(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)} = 0$

Step 2.16

Divide $0$ by $(1 - \frac{1}{\cos (x)}) (\sin^{2} (x) + 3 \cos (x) - 3)$ .

$0 = 0$

Step 3

Since $0 = 0$ , the equation will always be true for any value of $x$ .

All real numbers

Step 4

The result can be shown in multiple forms.

All real numbers

Interval Notation:

$(- \infty, \infty)$