Insanely easy question - trig functions, need a quick question answered

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andrew.c
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Homework Statement


I need to solve the equation [tex]cos 5x + cos 3x = cos x[/tex]

Do the first two terms add together to be cos 8x? Then use double angle formula to solve?
 

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andrew.c said:

Homework Statement


I need to solve the equation [tex]cos 5x + cos 3x = cos x[/tex]

Do the first two terms add together to be cos 8x? Then use double angle formula to solve?

No. cos 5x + cos 3x is not equal to cos8x.
Use formula to convert sum of trig. function to product form.