SOLUTION: using double angle formula find all values of x such 0� < x < 360� for which a) 2cos 2x= 3-2 cos x giv ans to 0.1 plz help it's confusing thx

Question 1120454: using double angle formula
find all values of x such 0� < x < 360� for which
a) 2cos 2x= 3-2 cos x
giv ans to 0.1
plz help it's confusing
thx
Found 2 solutions by solver91311, greenestamps:
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

Tell me why it is confusing and I will help you.

John

My calculator said it, I believe it, that settles it

Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

You have three basic identities for cos(2x). Since the rest of the equation contains a term involving cos(x), use the identity for cos(2x) that contains only cos(x). That will give you a quadratic equation in cos(x).

The equation won't factor; you will need to use the quadratic formula or something like a graphing calculator to find the value(s) of cos(x) that satisfy the equation.

If you use a graphing calculator, you will get the solutions for x. If you use the quadratic formula, what you will get is values of cos(x); then of course to find the values of x you will need to use the inverse cosine function.
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