SOLUTION: Range of function f(x)=1/(2-cos3x)

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Question 1031448: Range of function f(x)=1/(2-cos3x)
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
It is a fact that -1+%3C=+cos3x+%3C=+1 for all real values x.
==> 1+%3E=+-cos3x+%3E=+-1
==> 3+%3E=+2-cos3x+%3E=+1, after adding 2 to all sides..
==> 1%2F3+%3C=+1%2F%282-cos3x%29+%3C=+1, after inversion (notice that all terms are positive)
==> The range of f(x) is the closed interval [1/3, 1].