CHAPTER 20 REVIEW EXERCISES

CONCEPT CHECK EXERCISES

Determine each of the following as being either true or false. If it is false, explain why.

  1. tan 2θ = cos 2θsin 2θ

  2. cos2 2α = 1 − sin2 2α

  3. cos(α − β) = cos α cos β − sin α sin β

  4. sinα2 = 1 − cos α2

  5. sin − 1( − 1) = 3π2

  6. For 0 ≤ θ < 2π ,  the solution of the equation 2 cos θ + 1 = 0 is θ = 2π / 3 ,  4π / 3.

PRACTICE AND APPLICATIONS

In Exercises 714, determine the values of the indicated functions in the given manner.

  1. Find sin 120 °  by using 120 °  = 90 °  + 30 °  . 

  2. Find cos 30 °  by using 30 °  = 90 °  − 60 °  . 

  3. Find sin 315 °  by using 315 °  = 360 °  − 45 °  . 

  4. Find tan5π4 by using 5π4 = π + π4 . 

  5. Find cos π by using π = 2(π2) . 

  6. Find sin3π2 by using 3π2 = 2(3π4) . 

  7. Find tan 60 °  by using ...

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