How/Why do you get the solutions to a trigonometry equation with multiple angles?

Explain why the solutions to #cos(2x)=((sqrt(2))/2)# of the interval #[0,2pi)# are what they are!

1 Answer
Nov 9, 2015

For the example #cos(2x)=(sqrt2/2)#, the reason the answers #{pi/4, (7pi)/4, (9pi)/4, (15pi)/4}# are in the first and fourth quadrant are because cosine is positive in those quadrants. That is what is asking for.

Explanation:

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Realized my mistake and answered my own question. I had not realized it was a cosine and wasn't thinking about the quadrants.