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

  2.   If x and y are acute angles such that sin x = and sin y = , what is the value of cos (x - y)?
    A. B.
    C. D.
    Hint

  3.   Use the sum or difference identity for cosine to find the exact value of cos 105°
    A. B.
    C. D.
    Hint

  4.   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

  5.   Complete the identity tan ( - A) = ________.
    A. -tan A B. -cot A
    C. tan A D. cot A
    Hint



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