# Thread: period of trig function

1. ## period of trig function

Write down the period of the graph of y=3/(2+(cos2x)^2), and also the coordinates of a maximum value of y.

For the second question I answered correctly.
For the first, however I didnt.
It seems obvious to me that the period is 90, due to x being multiplied by 2 and the expression being squared; however the answer is 180.
Its also clear by the graph that the period is 90; is this a typo?

modified.

3. ## Re: period of trig function

Originally Posted by furor celtica
Write down the period of the graph of y=3/(2+(cos2x)^2), and also the coordinates of a maximum value of y.

For the second question I answered correctly.
For the first, however I didnt.
It seems obvious to me that the period is 90, due to x being multiplied by 2 and the expression being squared; however the answer is 180.
Its also clear by the graph that the period is 90; is this a typo?
If it's $y = \frac3{2+(\cos(2x))^2}$ then your answer 90º is correct. If it was supposed to be $y = \frac3{(2+\cos(2x))^2}$ then it would be 180º (but in that case the coordinates for the max value of y would be different).