Trigonometry Examples

tan (θ) = - \frac{3}{5}

$\tan (θ) = - \frac{3}{5}$ ,

cos (θ) > 0

$\cos (θ) > 0$

Step 1

The cosine function is positive in the first and fourth quadrants. The tangent function is negative in the second and fourth quadrants. The set of solutions for

θ

$θ$ are limited to the fourth quadrant since that is the only quadrant found in both sets.

Solution is in the fourth quadrant.

Step 2

Use the definition of tangent to find the known sides of the unit circle right triangle. The quadrant determines the sign on each of the values.

tan (θ) = \frac{opposite}{adjacent}

$\tan (θ) = \frac{opposite}{adjacent}$

Step 3

Find the hypotenuse of the unit circle triangle. Since the opposite and adjacent sides are known, use the Pythagorean theorem to find the remaining side.

Hypotenuse = \sqrt{{opposite}^{2} + {adjacent}^{2}}

$Hypotenuse = \sqrt{{opposite}^{2} + {adjacent}^{2}}$

Step 4

Replace the known values in the equation.

Hypotenuse = \sqrt{{(- 3)}^{2} + {(5)}^{2}}

$Hypotenuse = \sqrt{{(- 3)}^{2} + {(5)}^{2}}$

Step 5

Simplify inside the radical.

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Step 5.1

Raise

- 3

$- 3$ to the power of

2

$2$ .

Hypotenuse

= \sqrt{9 + {(5)}^{2}}

$= \sqrt{9 + {(5)}^{2}}$

Step 5.2

Raise

5

$5$ to the power of

2

$2$ .

Hypotenuse

= \sqrt{9 + 25}

$= \sqrt{9 + 25}$

Step 5.3

Add

9

$9$ and

25

$25$ .

Hypotenuse

= \sqrt{34}

$= \sqrt{34}$

Hypotenuse

= \sqrt{34}

$= \sqrt{34}$

Step 6

Find the value of sine.

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Step 6.1

Use the definition of sine to find the value of

sin (θ)

$\sin (θ)$ .

sin (θ) = \frac{opp}{hyp}

$\sin (θ) = \frac{opp}{hyp}$

Step 6.2

Substitute in the known values.

sin (θ) = \frac{- 3}{\sqrt{34}}

$\sin (θ) = \frac{- 3}{\sqrt{34}}$

Step 6.3

Simplify the value of

sin (θ)

$\sin (θ)$ .

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Step 6.3.1

Move the negative in front of the fraction.

sin (θ) = - \frac{3}{\sqrt{34}}

$\sin (θ) = - \frac{3}{\sqrt{34}}$

Step 6.3.2

Multiply

\frac{3}{\sqrt{34}}

$\frac{3}{\sqrt{34}}$ by

\frac{\sqrt{34}}{\sqrt{34}}

$\frac{\sqrt{34}}{\sqrt{34}}$ .

sin (θ) = - (\frac{3}{\sqrt{34}} \cdot \frac{\sqrt{34}}{\sqrt{34}})

$\sin (θ) = - (\frac{3}{\sqrt{34}} \cdot \frac{\sqrt{34}}{\sqrt{34}})$

Step 6.3.3

Combine and simplify the denominator.

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Step 6.3.3.1

Multiply

\frac{3}{\sqrt{34}}

$\frac{3}{\sqrt{34}}$ by

\frac{\sqrt{34}}{\sqrt{34}}

$\frac{\sqrt{34}}{\sqrt{34}}$ .

sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}

$\sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 6.3.3.2

Raise

\sqrt{34}

$\sqrt{34}$ to the power of

1

$1$ .

sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}

$\sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 6.3.3.3

Raise

\sqrt{34}

$\sqrt{34}$ to the power of

1

$1$ .

sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}

$\sin (θ) = - \frac{3 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 6.3.3.4

Use the power rule

a^{m} a^{n} = a^{m + n}

$a^{m} a^{n} = a^{m + n}$ to combine exponents.

sin (θ) = - \frac{3 \sqrt{34}}{{\sqrt{34}}^{1 + 1}}

$\sin (θ) = - \frac{3 \sqrt{34}}{{\sqrt{34}}^{1 + 1}}$

Step 6.3.3.5

Add

1

$1$ and

1

$1$ .

sin (θ) = - \frac{3 \sqrt{34}}{{\sqrt{34}}^{2}}

$\sin (θ) = - \frac{3 \sqrt{34}}{{\sqrt{34}}^{2}}$

Step 6.3.3.6

Rewrite

{\sqrt{34}}^{2}

${\sqrt{34}}^{2}$ as

34

$34$ .

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Step 6.3.3.6.1

Use

\sqrt[n]{a^{x}} = a^{\frac{x}{n}}

$\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite

\sqrt{34}

$\sqrt{34}$ as

34^{\frac{1}{2}}

$34^{\frac{1}{2}}$ .

sin (θ) = - \frac{3 \sqrt{34}}{{(34^{\frac{1}{2}})}^{2}}

$\sin (θ) = - \frac{3 \sqrt{34}}{{(34^{\frac{1}{2}})}^{2}}$

Step 6.3.3.6.2

Apply the power rule and multiply exponents,

{(a^{m})}^{n} = a^{m n}

${(a^{m})}^{n} = a^{m n}$ .

sin (θ) = - \frac{3 \sqrt{34}}{34^{\frac{1}{2} \cdot 2}}

$\sin (θ) = - \frac{3 \sqrt{34}}{34^{\frac{1}{2} \cdot 2}}$

Step 6.3.3.6.3

Combine

\frac{1}{2}

$\frac{1}{2}$ and

2

$2$ .

sin (θ) = - \frac{3 \sqrt{34}}{34^{\frac{2}{2}}}

$\sin (θ) = - \frac{3 \sqrt{34}}{34^{\frac{2}{2}}}$

Step 6.3.3.6.4

Cancel the common factor of

2

$2$ .

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Step 6.3.3.6.4.1

Cancel the common factor.

$\sin (θ) = - \frac{3 \sqrt{34}}{34^{\frac{2}{2}}}$

Step 6.3.3.6.4.2

Rewrite the expression.

$\sin (θ) = - \frac{3 \sqrt{34}}{34}$

Step 6.3.3.6.5

Evaluate the exponent.

$\sin (θ) = - \frac{3 \sqrt{34}}{34}$

Step 7

Find the value of cosine.

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Step 7.1

Use the definition of cosine to find the value of

$\cos (θ)$ .

$\cos (θ) = \frac{adj}{hyp}$

Step 7.2

Substitute in the known values.

$\cos (θ) = \frac{5}{\sqrt{34}}$

Step 7.3

Simplify the value of

$\cos (θ)$ .

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Step 7.3.1

Multiply

$\frac{5}{\sqrt{34}}$ by

$\frac{\sqrt{34}}{\sqrt{34}}$ .

$\cos (θ) = \frac{5}{\sqrt{34}} \cdot \frac{\sqrt{34}}{\sqrt{34}}$

Step 7.3.2

Combine and simplify the denominator.

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Step 7.3.2.1

Multiply

$\frac{5}{\sqrt{34}}$ by

$\frac{\sqrt{34}}{\sqrt{34}}$ .

$\cos (θ) = \frac{5 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 7.3.2.2

Raise

$\sqrt{34}$ to the power of

$1$ .

$\cos (θ) = \frac{5 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 7.3.2.3

Raise

$\sqrt{34}$ to the power of

$1$ .

$\cos (θ) = \frac{5 \sqrt{34}}{\sqrt{34} \sqrt{34}}$

Step 7.3.2.4

Use the power rule

$a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\cos (θ) = \frac{5 \sqrt{34}}{{\sqrt{34}}^{1 + 1}}$

Step 7.3.2.5

Add

$1$ and

$1$ .

$\cos (θ) = \frac{5 \sqrt{34}}{{\sqrt{34}}^{2}}$

Step 7.3.2.6

Rewrite

${\sqrt{34}}^{2}$ as

$34$ .

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Step 7.3.2.6.1

Use

$\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite

$\sqrt{34}$ as

$34^{\frac{1}{2}}$ .

$\cos (θ) = \frac{5 \sqrt{34}}{{(34^{\frac{1}{2}})}^{2}}$

Step 7.3.2.6.2

Apply the power rule and multiply exponents,

${(a^{m})}^{n} = a^{m n}$ .

$\cos (θ) = \frac{5 \sqrt{34}}{34^{\frac{1}{2} \cdot 2}}$

Step 7.3.2.6.3

Combine

$\frac{1}{2}$ and

$2$ .

$\cos (θ) = \frac{5 \sqrt{34}}{34^{\frac{2}{2}}}$

Step 7.3.2.6.4

Cancel the common factor of

$2$ .

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Step 7.3.2.6.4.1

Cancel the common factor.

$\cos (θ) = \frac{5 \sqrt{34}}{34^{\frac{2}{2}}}$

Step 7.3.2.6.4.2

Rewrite the expression.

$\cos (θ) = \frac{5 \sqrt{34}}{34}$

Step 7.3.2.6.5

Evaluate the exponent.

$\cos (θ) = \frac{5 \sqrt{34}}{34}$

Step 8

Find the value of cotangent.

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Step 8.1

Use the definition of cotangent to find the value of

$\cot (θ)$ .

$\cot (θ) = \frac{adj}{opp}$

Step 8.2

Substitute in the known values.

$\cot (θ) = \frac{5}{- 3}$

Step 8.3

Move the negative in front of the fraction.

$\cot (θ) = - \frac{5}{3}$

Step 9

Find the value of secant.

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Step 9.1

Use the definition of secant to find the value of

$\sec (θ)$ .

$\sec (θ) = \frac{hyp}{adj}$

Step 9.2

Substitute in the known values.

$\sec (θ) = \frac{\sqrt{34}}{5}$

Step 10

Find the value of cosecant.

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Step 10.1

Use the definition of cosecant to find the value of

$\csc (θ)$ .

$\csc (θ) = \frac{hyp}{opp}$

Step 10.2

Substitute in the known values.

$\csc (θ) = \frac{\sqrt{34}}{- 3}$

Step 10.3

Move the negative in front of the fraction.

$\csc (θ) = - \frac{\sqrt{34}}{3}$

Step 11

This is the solution to each trig value.

$\sin (θ) = - \frac{3 \sqrt{34}}{34}$

$\cos (θ) = \frac{5 \sqrt{34}}{34}$

$\tan (θ) = - \frac{3}{5}$

$\cot (θ) = - \frac{5}{3}$

$\sec (θ) = \frac{\sqrt{34}}{5}$

$\csc (θ) = - \frac{\sqrt{34}}{3}$