Trigonometry Examples

$(\frac{\sin (s - t)}{\sin (t)}) + (\frac{\cos (s - t)}{\cos (t)}) = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1

Simplify the left side.

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Step 1.1

Simplify each term.

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Step 1.1.1

Rewrite $\frac{\sin (s - t)}{\sin (t)}$ as a product.

$\sin (s - t) \frac{1}{\sin (t)} + \frac{\cos (s - t)}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.2

Write $\sin (s - t)$ as a fraction with denominator $1$ .

$\frac{\sin (s - t)}{1} \cdot \frac{1}{\sin (t)} + \frac{\cos (s - t)}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.3

Simplify.

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Step 1.1.3.1

Divide $\sin (s - t)$ by $1$ .

$\sin (s - t) \frac{1}{\sin (t)} + \frac{\cos (s - t)}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.3.2

Convert from $\frac{1}{\sin (t)}$ to $\csc (t)$ .

$\sin (s - t) \csc (t) + \frac{\cos (s - t)}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.4

Rewrite $\frac{\cos (s - t)}{\cos (t)}$ as a product.

$\sin (s - t) \csc (t) + \cos (s - t) \frac{1}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.5

Write $\cos (s - t)$ as a fraction with denominator $1$ .

$\sin (s - t) \csc (t) + \frac{\cos (s - t)}{1} \cdot \frac{1}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.6

Simplify.

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Step 1.1.6.1

Divide $\cos (s - t)$ by $1$ .

$\sin (s - t) \csc (t) + \cos (s - t) \frac{1}{\cos (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 1.1.6.2

Convert from $\frac{1}{\cos (t)}$ to $\sec (t)$ .

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 2

Simplify the right side.

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Step 2.1

Simplify $\frac{\sin (s)}{\sin (t) \cos (t)}$ .

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Step 2.1.1

Separate fractions.

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{1}{\cos (t)} \cdot \frac{\sin (s)}{\sin (t)}$

Step 2.1.2

Rewrite $\frac{\sin (s)}{\sin (t)}$ as a product.

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{1}{\cos (t)} (\sin (s) \frac{1}{\sin (t)})$

Step 2.1.3

Write $\sin (s)$ as a fraction with denominator $1$ .

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{1}{\cos (t)} (\frac{\sin (s)}{1} \cdot \frac{1}{\sin (t)})$

Step 2.1.4

Simplify.

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Step 2.1.4.1

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

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{1}{\cos (t)} (\sin (s) \frac{1}{\sin (t)})$

Step 2.1.4.2

Convert from $\frac{1}{\sin (t)}$ to $\csc (t)$ .

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \frac{1}{\cos (t)} (\sin (s) \csc (t))$

Step 2.1.5

Convert from $\frac{1}{\cos (t)}$ to $\sec (t)$ .

$\sin (s - t) \csc (t) + \cos (s - t) \sec (t) = \sec (t) \sin (s) \csc (t)$

Step 3

Simplify $\sin (s - t) \csc (t) + \cos (s - t) \sec (t)$ .

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Step 3.1

Simplify each term.

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Step 3.1.1

Rewrite $\csc (t)$ in terms of sines and cosines.

$\sin (s - t) \frac{1}{\sin (t)} + \cos (s - t) \sec (t) = \sec (t) \sin (s) \csc (t)$

Step 3.1.2

Combine $\sin (s - t)$ and $\frac{1}{\sin (t)}$ .

$\frac{\sin (s - t)}{\sin (t)} + \cos (s - t) \sec (t) = \sec (t) \sin (s) \csc (t)$

Step 3.1.3

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

$\frac{\sin (s - t)}{\sin (t)} + \cos (s - t) \frac{1}{\cos (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.1.4

Combine $\cos (s - t)$ and $\frac{1}{\cos (t)}$ .

$\frac{\sin (s - t)}{\sin (t)} + \frac{\cos (s - t)}{\cos (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.2

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

$\frac{\sin (s - t)}{\sin (t)} \cdot \frac{\cos (t)}{\cos (t)} + \frac{\cos (s - t)}{\cos (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.3

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

$\frac{\sin (s - t)}{\sin (t)} \cdot \frac{\cos (t)}{\cos (t)} + \frac{\cos (s - t)}{\cos (t)} \cdot \frac{\sin (t)}{\sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.4

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

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Step 3.4.1

Multiply $\frac{\sin (s - t)}{\sin (t)}$ by $\frac{\cos (t)}{\cos (t)}$ .

$\frac{\sin (s - t) \cos (t)}{\sin (t) \cos (t)} + \frac{\cos (s - t)}{\cos (t)} \cdot \frac{\sin (t)}{\sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.4.2

Multiply $\frac{\cos (s - t)}{\cos (t)}$ by $\frac{\sin (t)}{\sin (t)}$ .

$\frac{\sin (s - t) \cos (t)}{\sin (t) \cos (t)} + \frac{\cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.4.3

Reorder the factors of $\sin (t) \cos (t)$ .

$\frac{\sin (s - t) \cos (t)}{\cos (t) \sin (t)} + \frac{\cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 3.5

Combine the numerators over the common denominator.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 4

Simplify $\sec (t) \sin (s) \csc (t)$ .

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Step 4.1

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

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} \sin (s) \csc (t)$

Step 4.2

Combine $\frac{1}{\cos (t)}$ and $\sin (s)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\cos (t)} \csc (t)$

Step 4.3

Rewrite $\csc (t)$ in terms of sines and cosines.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\cos (t)} \cdot \frac{1}{\sin (t)}$

Step 4.4

Multiply $\frac{\sin (s)}{\cos (t)}$ by $\frac{1}{\sin (t)}$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\cos (t) \sin (t)}$

Step 4.5

Separate fractions.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} \cdot \frac{\sin (s)}{\cos (t)}$

Step 4.6

Rewrite $\frac{\sin (s)}{\cos (t)}$ as a product.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} (\sin (s) \frac{1}{\cos (t)})$

Step 4.7

Write $\sin (s)$ as a fraction with denominator $1$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} (\frac{\sin (s)}{1} \cdot \frac{1}{\cos (t)})$

Step 4.8

Simplify.

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Step 4.8.1

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

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} (\sin (s) \frac{1}{\cos (t)})$

Step 4.8.2

Convert from $\frac{1}{\cos (t)}$ to $\sec (t)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} (\sin (s) \sec (t))$

Step 4.9

Convert from $\frac{1}{\sin (t)}$ to $\csc (t)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \csc (t) \sin (s) \sec (t)$

Step 5

Simplify $\csc (t) \sin (s) \sec (t)$ .

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Step 5.1

Rewrite $\csc (t)$ in terms of sines and cosines.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\sin (t)} \sin (s) \sec (t)$

Step 5.2

Combine $\frac{1}{\sin (t)}$ and $\sin (s)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\sin (t)} \sec (t)$

Step 5.3

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

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\sin (t)} \cdot \frac{1}{\cos (t)}$

Step 5.4

Multiply $\frac{\sin (s)}{\sin (t)}$ by $\frac{1}{\cos (t)}$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{\sin (s)}{\sin (t) \cos (t)}$

Step 5.5

Separate fractions.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} \cdot \frac{\sin (s)}{\sin (t)}$

Step 5.6

Rewrite $\frac{\sin (s)}{\sin (t)}$ as a product.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} (\sin (s) \frac{1}{\sin (t)})$

Step 5.7

Write $\sin (s)$ as a fraction with denominator $1$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} (\frac{\sin (s)}{1} \cdot \frac{1}{\sin (t)})$

Step 5.8

Simplify.

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Step 5.8.1

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

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} (\sin (s) \frac{1}{\sin (t)})$

Step 5.8.2

Convert from $\frac{1}{\sin (t)}$ to $\csc (t)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \frac{1}{\cos (t)} (\sin (s) \csc (t))$

Step 5.9

Convert from $\frac{1}{\cos (t)}$ to $\sec (t)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} = \sec (t) \sin (s) \csc (t)$

Step 6

Move all terms containing $s$ to the left side of the equation.

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Step 6.1

Subtract $\sec (t) \sin (s) \csc (t)$ from both sides of the equation.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \sec (t) \sin (s) \csc (t) = 0$

Step 6.2

Simplify each term.

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Step 6.2.1

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

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \frac{1}{\cos (t)} \sin (s) \csc (t) = 0$

Step 6.2.2

Combine $\sin (s)$ and $\frac{1}{\cos (t)}$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \frac{\sin (s)}{\cos (t)} \csc (t) = 0$

Step 6.2.3

Rewrite $\csc (t)$ in terms of sines and cosines.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \frac{\sin (s)}{\cos (t)} \cdot \frac{1}{\sin (t)} = 0$

Step 6.2.4

Multiply $\frac{1}{\sin (t)}$ by $\frac{\sin (s)}{\cos (t)}$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \frac{\sin (s)}{\sin (t) \cos (t)} = 0$

Step 6.3

Reorder the factors of $\sin (t) \cos (t)$ .

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t)}{\cos (t) \sin (t)} - \frac{\sin (s)}{\cos (t) \sin (t)} = 0$

Step 6.4

Combine the numerators over the common denominator.

$\frac{\sin (s - t) \cos (t) + \cos (s - t) \sin (t) - \sin (s)}{\cos (t) \sin (t)} = 0$