1.   Use the sum or difference identity for sine to find the exact value
of sin 375°.
    A. B.
    C. D.
    Hint

  2.   Use the sum or difference identity for tangent to find the exact value
of tan 255°.
    A. B.
    C. D.
    Hint

  3.   Use the sum or difference identity for tangent to find the exact value of tan 165°.
    A. 1 B. -
    C. - 2 D.
    Hint

  4.   Find the value of cos (x - y) if 0 < x < , 0 < y < , sin x = , and cos y = .
    A. B.
    C. D.
    Hint

  5.   If angles x and y are between 0° and 180° such that cos x = - and cos y = , what is the value of sin (x + y)?
    A. B.
    C. D.
    Hint