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Math Help - Solve a system of equations involving trig functions

  1. #1
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    Solve a system of equations involving trig functions

    Im trying to solve these two equations by elimination. But im stuck at this point. This is for a Diff Equation class and i just cant recall some of the trig rules.

    -4cos(2x)-2sin(2x)p(x)+cos(2x)q(x)=0
    -4sin(2x)+2cos(2x)p(x)+sin(2x)q(x)=0

    Any help is appreciated. Thanks
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  2. #2
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    Re: Solve a system of equations involving trig functions

    You don't need trig rules, you need ALGEBRA rules. Choose which function you want to solve for (either p or q), which means you need to eliminate the other function.

    Say you want to eliminate p, you will need to multiply all the first equation by cos(2x) and all the second equation by sin(2x) so that p has the same coefficients in both equations, then add the equations.
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  3. #3
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    Re: Solve a system of equations involving trig functions

    OK, i understand. Thank you again Prove It.
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