1.   Find the value of sin (x + y) if , sin x = , and
sin y = .
    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. cot A B. tan A
    C. -cot A D. -tan A
    Hint