(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

#1. Solve the system:

3cos(a) + cos(b) +5sin(2a)=2

cos(a)=cos(b)+sin(2a)

7cos(a) + 13sin(2a)=-7cos(b)

3. The attempt at a solution

#1. I decided to substitute variables for sines and cosines. So I made cos(a) = x, cos(b)=y and sin(2a)=z, as a result of which, my equations now look like:

3x+y+5z=2

x-y-z=0

7z+7y+13z=0

after which I created the matrix, here is a picture of how I solved it. So I got -3/8 for "x" and entered it (it only asks for cos(a)), but it tells me I'm wrong. Am I being dumb and making some obvious error? Because I entered all equations with variable values into my calculator and they work out...

Thanks...

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# Homework Help: Matrix (2 actually)

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