SOLUTION: Solve 3cos2𝜃 + cos𝜃 = 2 for 0 < 𝜃 < 360°.

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Question 1163480: Solve 3cos2𝜃 + cos𝜃 = 2 for 0 < 𝜃 < 360°.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!




Use the Double Angle Formula -- the form that only has cosine in it.





Let



The quadratic factors



So



or



And then



or



or



These are the exact answers. Use your calculator to find decimal approximations. My answers are in radians; you can convert to degrees if you like.


John

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