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7.4 The Other Trigonometric Functions

Secant, cosecant, tangent, and cotangent: exact values, even-odd symmetry, Pythagorean identities, and calculator use.

Algebra and Trigonometry 2e, 7.4 The Other Trigonometric Functions

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83 exercises

Finding the Trigonometric Functions of an Angle

Find sint,cost,tant,sect,csct, \sin t , \cos t , \tan t , \sec t , \csc t , and cott. \cot t . when t= π 6 . t = \frac{\pi}{6} .

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7.4 Exercise 4

Find sint,cost,tant,sect,csct, \sin t , \cos t , \tan t , \sec t , \csc t , and cott. \cot t . when t= π 3 . t = \frac{\pi}{3} .

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Using Reference Angles to Find Trigonometric Functions

Use reference angles to find all six trigonometric functions of − 5π 6 . - \frac{5 \pi}{6} .

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7.4 Exercise 6

Use reference angles to find all six trigonometric functions of − 7π 4 . - \frac{7 \pi}{4} .

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Using Even and Odd Properties of Trigonometric Functions

If the secant of angle t t is 2, what is the secant of −t? − t ?

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7.4 Exercise 8

If the cotangent of angle t t is 3 , \sqrt{3} , what is the cotangent of −t? − t ?

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Using Identities to Evaluate Trigonometric Functions

  1. ⓐ Given sin(45°)= 2 2 ,cos(45°)= 2 2 , \sin \left(45°\right) = \frac{\sqrt{2}}{2} , \cos \left(45°\right) = \frac{\sqrt{2}}{2} , evaluate tan(45°). \tan \left(45°\right) .
  2. ⓑ Given sin( 5π 6 )= 1 2 ,cos( 5π 6 )=− 3 2 , \sin \left(\frac{5 \pi}{6}\right) = \frac{1}{2} , \cos \left(\frac{5 \pi}{6}\right) = - \frac{\sqrt{3}}{2} , evaluate sec( 5π 6 ). \sec \left(\frac{5 \pi}{6}\right) .
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7.4 Exercise 10

Evaluate csc( 7π 6 ). \text{csc} \left(\frac{7 \pi}{6}\right) .

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Using Identities to Simplify Trigonometric Expressions

Simplify sect tant . \frac{\sec t}{\tan t} .

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7.4 Exercise 12

Simplify (tant)(cost). \left(\tan t\right) \left(\cos t\right) .

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7.4 Exercise 14

If sec(t)=− 17 8 \sec \left(t\right) = - \frac{17}{8} and 0<t<π, 0 < t < \pi , find the values of the other five functions.

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Finding the Value of Trigonometric Functions

If sin(t)=− 3 2 andcos(t)= 1 2 ,findsec(t),csc(t),tan(t),cot(t). \sin \left(t\right) = - \frac{\sqrt{3}}{2} \text{and} \text{cos} \left(t\right) = \frac{1}{2} , \text{find} \text{sec} \left(t\right) , \text{csc} \left(t\right) , \text{tan} \left(t\right) , \text{cot} \left(t\right) .

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7.4 Exercise 18

sin(t)= 2 2 andcos(t)= 2 2 ,findsec(t),csc(t),tan(t),andcot(t) \sin \left(t\right) = \frac{\sqrt{2}}{2} \text{and} \cos \left(t\right) = \frac{\sqrt{2}}{2} , \text{find} \text{sec} \left(t\right) , \text{csc} \left(t\right) , \text{tan} \left(t\right) , \text{and} \text{cot} \left(t\right)

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Evaluating the Cosecant Using Technology

Evaluate the cosecant of 5π 7 . \frac{5 \pi}{7} .

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7.4 Exercise 20

Evaluate the cotangent of − π 8 . - \frac{\pi}{8} .

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7.4 Exercise 21

On an interval of [ 0,2π ), \left[0 , 2 \pi\right) , can the sine and cosine values of a radian measure ever be equal? If so, where?

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7.4 Exercise 23

For any angle in quadrant II, if you knew the sine of the angle, how could you determine the cosine of the angle?

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7.4 Exercise 25

Tangent and cotangent have a period of π. \pi . What does this tell us about the output of these functions?

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7.4 Exercise 27

Find the exact value of each expression.

sec π 6 \sec \frac{\pi}{6}

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7.4 Exercise 29

Find the exact value of each expression.

cot π 6 \cot \frac{\pi}{6}

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7.4 Exercise 31

Find the exact value of each expression.

sec π 4 \sec \frac{\pi}{4}

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7.4 Exercise 33

Find the exact value of each expression.

cot π 4 \cot \frac{\pi}{4}

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7.4 Exercise 35

Find the exact value of each expression.

sec π 3 \sec \frac{\pi}{3}

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7.4 Exercise 37

Find the exact value of each expression.

cot π 3 \cot \frac{\pi}{3}

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7.4 Exercise 39

Use reference angles to evaluate the expression.

sec 7π 6 \sec \frac{7 \pi}{6}

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7.4 Exercise 41

Use reference angles to evaluate the expression.

cot 13π 6 \cot \frac{13 \pi}{6}

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7.4 Exercise 43

Use reference angles to evaluate the expression.

sec 3π 4 \sec \frac{3 \pi}{4}

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7.4 Exercise 45

Use reference angles to evaluate the expression.

cot 11π 4 \cot \frac{11 \pi}{4}

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7.4 Exercise 47

Use reference angles to evaluate the expression.

sec 4π 3 \sec \frac{4 \pi}{3}

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7.4 Exercise 49

Use reference angles to evaluate the expression.

cot 5π 3 \cot \frac{5 \pi}{3}

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7.4 Exercise 51

Use reference angles to evaluate the expression.

sec300° \sec 300°

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7.4 Exercise 53

Use reference angles to evaluate the expression.

cot240° \cot 240°

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7.4 Exercise 55

Use reference angles to evaluate the expression.

sec120° \sec 120°

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7.4 Exercise 57

Use reference angles to evaluate the expression.

cot315° \cot 315°

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7.4 Exercise 59

Use reference angles to evaluate the expression.

If cost=− 1 3 , \text{cos} t = - \frac{1}{3} , and t t is in quadrant III, find sint,sect,csct,tant, \sin t , \sec t , \csc t , \tan t , and cott. \cot t .

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7.4 Exercise 61

Use reference angles to evaluate the expression.

If sint= 3 2 \sin t = \frac{\sqrt{3}}{2} and cost= 1 2 , \cos t = \frac{1}{2} , find sect,csct,tant, \sec t , \csc t , \tan t , and cott. \cot t .

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7.4 Exercise 63

Use reference angles to evaluate the expression.

If sint= 2 2 , \text{sin} t = \frac{\sqrt{2}}{2} , what is the sin(−t)? \text{sin} \left(− t\right) ?

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7.4 Exercise 65

Use reference angles to evaluate the expression.

If sect=3.1, \text{sec} t = 3.1 , what is the sec(−t)? \text{sec} \left(− t\right) ?

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7.4 Exercise 67

Use reference angles to evaluate the expression.

If tant=−1.4, \text{tan} t = −1.4 , what is the tan(−t)? \text{tan} \left(− t\right) ?

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7.4 Exercise 73

Use a graphing calculator to evaluate to three decimal places.

cot 4π 7 \cot \frac{4 \pi}{7}

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7.4 Exercise 75

Use a graphing calculator to evaluate to three decimal places.

tan 5π 8 \tan \frac{5 \pi}{8}

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7.4 Exercise 77

Use a graphing calculator to evaluate to three decimal places.

csc π 4 \csc \frac{\pi}{4}

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7.4 Exercise 79

Use a graphing calculator to evaluate to three decimal places.

cot33° \cot 33°

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7.4 Exercise 81

Use a graphing calculator to evaluate to three decimal places.

sec310° \sec 310°

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7.4 Exercise 83

Use identities to evaluate the expression.

If tan( t )≈1.3, \tan \left(t\right) \approx 1.3 , and cos( t )≈0.61, \cos \left(t\right) \approx 0.61 , find sin( t ). \sin \left(t\right) .

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7.4 Exercise 85

Use identities to evaluate the expression.

If cot( t )≈0.58, \cot \left(t\right) \approx 0.58 , and cos( t )≈0.5, \cos \left(t\right) \approx 0.5 , find csc( t ). \csc \left(t\right) .

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7.4 Exercise 87

Use identities to evaluate the expression.

Determine whether the function f(x)=3 sin 2 xcosx+secx f \left(x\right) = 3 \sin^{2} x \cos x + \sec x is even, odd, or neither.

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7.4 Exercise 89

Use identities to evaluate the expression.

Determine whether the function f(x)= csc 2 x+secx f \left(x\right) = \csc^{2} x + \sec x is even, odd, or neither.

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7.4 Exercise 91

Use identities to simplify the expression.

sect csct \frac{\sec t}{\csc t}

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7.4 Exercise 93

The amount of sunlight in a certain city can be modeled by the function h=16cos( 1 500 d ), h = 16 \cos \left(\frac{1}{500} d\right) , where h h represents the hours of sunlight, and d d is the day of the year. Use the equation to find how many hours of sunlight there are on September 24, the 267th day of the year. State the period of the function.

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7.4 Exercise 95

The height of a piston, h, h , in inches, can be modeled by the equation y=3sinx+1, y = 3 \sin x + 1 , where x x represents the crank angle. Find the height of the piston when the crank angle is 55°. 55° .

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7.4 Exercise 97

Convert the angle measures to degrees.

π 4 \frac{\pi}{4}

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7.4 Exercise 99

Convert the angle measures to radians.

−210° −210°

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7.4 Exercise 101

Convert the angle measures to radians.

Find the length of an arc in a circle of radius 7 meters subtended by the central angle of 85°. 85° .

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7.4 Exercise 103

Find the angle between 0° 0° and 360° \text{360}° that is coterminal with the given angle.

420° 420°

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7.4 Exercise 105

Find the angle between 0 and 2π 2 \pi in radians that is coterminal with the given angle.

− 20π 11 - \frac{20 \pi}{11}

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7.4 Exercise 111

Draw the angle provided in standard position on the Cartesian plane.

Find the linear speed of a point on the equator of the earth if the earth has a radius of 3,960 miles and the earth rotates on its axis every 24 hours. Express answer in miles per hour. Round to the nearest hundredth.

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7.4 Exercise 113

Use side lengths to evaluate.

cos π 4 \cos \frac{\pi}{4}

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7.4 Exercise 115

Use side lengths to evaluate.

tan π 6 \tan \frac{\pi}{6}

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7.4 Exercise 117

Use side lengths to evaluate.

csc( 18° )=sec( ___° ) \csc \left(18°\right) = \sec \left(___°\right)

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7.4 Exercise 119

Use the given information to find the lengths of the other two sides of the right triangle.

tanA= 5 9 ,b=6 \tan A = \frac{5}{9} , b = 6

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7.4 Exercise 121

tanB \tan B

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7.4 Exercise 125

Solve for the unknown sides of the given triangle.

The angle of elevation to the top of a building in Baltimore is found to be 4 degrees from the ground at a distance of 1 mile from the base of the building. Using this information, find the height of the building. Find the answer to four decimal places.

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7.4 Exercise 127

Find the exact value of cos π 4 . \cos \frac{\pi}{4} .

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7.4 Exercise 129

State the reference angle for 300°. 300° .

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7.4 Exercise 131

Compute cosine of 330°. 330° .

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7.4 Exercise 133

State the domain of the sine and cosine functions.

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7.4 Exercise 135

Find the exact value of the given expression.

cos π 6 \cos \frac{\pi}{6}

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7.4 Exercise 137

Find the exact value of the given expression.

csc π 3 \csc \frac{\pi}{3}

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7.4 Exercise 139

Use reference angles to evaluate the given expression.

sec 11π 3 \sec \frac{11 \pi}{3}

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7.4 Exercise 141

Use reference angles to evaluate the given expression.

If sec( t )=−2.5, \sec \left(t\right) = −2.5 , what is the sec(−t)? \text{sec} \left(- t\right) ?

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7.4 Exercise 143

Use reference angles to evaluate the given expression.

If tan(t)= 1 3 , \text{tan} \left(t\right) = \frac{1}{3} , find tan(t−π). \text{tan} \left(t - \pi\right) .

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7.4 Exercise 145

Use reference angles to evaluate the given expression.

Which trigonometric functions are even?

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7.4 Exercise 147

Convert 5π 6 \frac{5 \pi}{6} radians to degrees.

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7.4 Exercise 149

Find the length of a circular arc with a radius 12 centimeters subtended by the central angle of 30°. 30° .

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7.4 Exercise 151

Find the angle between 0° 0° and 360° \text{360}° that is coterminal with 375°. 375° .

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7.4 Exercise 155

A carnival has a Ferris wheel with a diameter of 80 feet. The time for the Ferris wheel to make one revolution is 75 seconds. What is the linear speed in feet per second of a point on the Ferris wheel? What is the angular speed in radians per second?

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7.4 Exercise 159

Find the exact value of sin π 6 . \sin \frac{\pi}{6} .

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7.4 Exercise 161

State the domain of the sine and cosine functions.

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7.4 Exercise 163

Find the exact value of cot π 4 . \cot \frac{\pi}{4} .

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7.4 Exercise 165

Use reference angles to evaluate csc 7π 4 . \csc \frac{7 \pi}{4} .

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7.4 Exercise 167

If csct=0.68, \text{csc} t = 0.68 , what is the csc(−t)? \text{csc} \left(- t\right) ?

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7.4 Exercise 169

Find the missing angle: cos( π 6 )=sin( ___ ) \cos \left(\frac{\pi}{6}\right) = \sin \left(___\right)

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.