SOLUTION: Hi, the problem cos^2 2x - sin^2 2x=0 is giving me trouble. I don't know what to do to solve it. Please help me. Thank you.

Question 138472This question is from textbook Algebra and Trigonometry
: Hi, the problem cos^2 2x - sin^2 2x=0 is giving me trouble. I don't know what to do to solve it. Please help me. Thank you. This question is from textbook Algebra and Trigonometry

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
cos^2 2x - sin^2 2x=0
----------------------------
cos^2(2x) - [ 1-cos^2(2x)] = 0
2cos^2(2x) = 1
cos^2(2x) = 1/2
---------------------
cos(2x) = sqrt(2)/2
2x = 45 degrees or -45 degrees
x = 22.5 degrees or -22.5 degrees
====================
Cheers,
Stan H.
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