I have this trig identity problem i need to solve(adsbygoogle = window.adsbygoogle || []).push({});

cos2x=cosx

I have to find all the values of x, and i know the answer is x=0°+120°, but i can figure ou how. I've tried it over and over and my answer turns out to x=0°=180°. Please help, thank you.:uhh:

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# I can't figure it out

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