How would I solve the trig equation 5 cos(2x)=2 ?????????????(Headbang)

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- Nov 11th 2012, 08:18 AMderek1008Need help with trigonometric equations please.
How would I solve the trig equation 5 cos(2x)=2 ?????????????(Headbang)

- Nov 11th 2012, 09:11 AMrichard1234Re: Need help with trigonometric equations please.

What angles within the unit circle have a cosine of 2/5? - Nov 11th 2012, 09:17 AMskeeterRe: Need help with trigonometric equations please.
assuming solutions in the interval ...

let , so

since , is an angle in quads I or IV

quad I solutions for , (two) ...

and

so and

quad IV solutions (two) ...

and

so and