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Math Help - sin a sinx+ b cosx

  1. #1
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    sin a sinx+ b cosx

    a)Express 2cosx+ sinx in the form Rcos(x-A)

    b) Solve the equation 2cosx+ sinx= 1 giving all solutions between 0 and 360 degrees.

    c) Find the exact range of values of the constant K for wich the equation 2cosx+sinx =K has real solutions for x

    Id really appreciate it if somone helped me with this question.
    I can do part a but not b and c

    Thank you.
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  2. #2
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    Quote Originally Posted by Oasis1993 View Post
    a)Express 2cosx+ sinx in the form Rcos(x-A)

    b) Solve the equation 2cosx+ sinx= 1 giving all solutions between 0 and 360 degrees.

    c) Find the exact range of values of the constant K for wich the equation 2cosx+sinx =K has real solutions for x

    Id really appreciate it if somone helped me with this question.
    I can do part a but not b and c

    Thank you.
    HI

    (b) \sqrt{5}\cos (x-26.57)=1

    \cos (x-26.57)=\frac{1}{\sqrt{5}}

    x-26.57=63.43 , 296.57

    Can you continue ?

    (c) \sqrt{5}\leq K\leq \sqrt{5}

    Graph \sqrt{5}\cos (x-26.57) and you should be able to see .
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