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5.3 The Other Trigonometric Functions

Tangent, secant, cosecant, and cotangent at special angles, even-odd behavior, Pythagorean and quotient identities, and calculator use.

Precalculus 2e, 5.3 The Other Trigonometric Functions

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51 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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5.3 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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5.3 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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5.3 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 ,evaluatesec( 5π 6 ). \sin \left(\frac{5 \pi}{6}\right) = \frac{1}{2} , \text{cos} \left(\frac{5 \pi}{6}\right) = - \frac{\sqrt{3}}{2} , \text{evaluate} \sec \left(\frac{5 \pi}{6}\right) .
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5.3 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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5.3 Exercise 12

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

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

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5.3 Exercise 18

If sin( t )= 2 2 \sin \left(t\right) = \frac{\sqrt{2}}{2} and cos( t )= 2 2 , \cos \left(t\right) = \frac{\sqrt{2}}{2} , find sec(t),csc(t),tan(t), and cot(t). \text{sec} \left(t\right) , \text{csc} \left(t\right) , \text{tan} \left(t\right) , \textrm{ }\text{and}\textrm{ }\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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5.3 Exercise 20

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

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5.3 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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5.3 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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5.3 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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5.3 Exercise 27

Find the exact value of each expression.

sec π 6 \sec \frac{\pi}{6}

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5.3 Exercise 29

Find the exact value of each expression.

cot π 6 \cot \frac{\pi}{6}

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5.3 Exercise 31

Find the exact value of each expression.

sec π 4 \sec \frac{\pi}{4}

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5.3 Exercise 33

Find the exact value of each expression.

cot π 4 \cot \frac{\pi}{4}

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5.3 Exercise 35

Find the exact value of each expression.

sec π 3 \sec \frac{\pi}{3}

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5.3 Exercise 37

Find the exact value of each expression.

cot π 3 \cot \frac{\pi}{3}

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5.3 Exercise 39

Use reference angles to evaluate the expression.

sec 7π 6 \sec \frac{7 \pi}{6}

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5.3 Exercise 41

Use reference angles to evaluate the expression.

cot 13π 6 \cot \frac{13 \pi}{6}

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5.3 Exercise 43

Use reference angles to evaluate the expression.

sec 3π 4 \sec \frac{3 \pi}{4}

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5.3 Exercise 45

Use reference angles to evaluate the expression.

cot 11π 4 \cot \frac{11 \pi}{4}

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5.3 Exercise 47

Use reference angles to evaluate the expression.

sec 4π 3 \sec \frac{4 \pi}{3}

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5.3 Exercise 49

Use reference angles to evaluate the expression.

cot 5π 3 \cot \frac{5 \pi}{3}

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5.3 Exercise 51

Use reference angles to evaluate the expression.

sec300° \sec 300°

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5.3 Exercise 53

Use reference angles to evaluate the expression.

cot240° \cot 240°

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5.3 Exercise 55

Use reference angles to evaluate the expression.

sec120° \sec 120°

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5.3 Exercise 57

Use reference angles to evaluate the expression.

cot315° \cot 315°

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5.3 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,cott. \sin t , \sec t , \csc t , \tan t , \cot t .

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5.3 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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5.3 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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5.3 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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5.3 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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5.3 Exercise 73

Use a graphing calculator to evaluate.

cot 4π 7 \cot \frac{4 \pi}{7}

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5.3 Exercise 75

Use a graphing calculator to evaluate.

tan 5π 8 \tan \frac{5 \pi}{8}

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5.3 Exercise 77

Use a graphing calculator to evaluate.

csc π 4 \csc \frac{\pi}{4}

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5.3 Exercise 79

Use a graphing calculator to evaluate.

cot33° \cot 33°

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5.3 Exercise 81

Use a graphing calculator to evaluate.

sec310° \sec 310°

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5.3 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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5.3 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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5.3 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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5.3 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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5.3 Exercise 91

Use identities to simplify the expression.

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

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5.3 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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5.3 Exercise 95

The height of a piston, h, h , in inches, can be modeled by the equation y=2cosx+6, y = 2 \cos x + 6 , where x x represents the crank angle. Find the height of the piston when the crank angle is 30°. 30 ° .

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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.