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Homework Help: Compund angle formula prob

  1. Nov 3, 2012 #1
    1. The problem statement, all variables and given/known data

    hello i am having trouble with a question here it is

    use an appropriate compound angle formula to express a a single trig formula than determine an exact formula for each

    a) sin pi/4 cos pi/12 +cos pi/4 sin pi/12

    so i got most of it i put it in to the fourmla sin(x+y)=sinxcosx+cosysinx

    i solved for the right side and got square root of 3 over 2
    but for the left side i am having trouble relating pi/12 to a special triangle as it is only 15
    so far i am only able to do
    sin pi/4 cos pi/12 + cos pi/4 sin pi/12
    1/sq root of2 + blank+1/sq of root 2 + blank

    as you can see i can solve the cos pi/12 and sin pi/12 if some one could please help me and show full steps as there is the same numbers for the diff compound formulas so i can see how to solve those
    thank you
  2. jcsd
  3. Nov 3, 2012 #2
    I have no idea what you are doing!
    The question looks like you have to use sin(A + B) to simplify the expression given.

    In which case it's just sin(pi/4 + pi/12).
    which is sin(pi/3)
  4. Nov 3, 2012 #3


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    Hello zycismia. Welcome to PF !

    That should be: (1/(sq root of 2)) (times) blank1 + (1/(sq of root 2)) (times) blank2 .
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