# Math Help - Periodic Function

1. ## Periodic Function

The picture shows a portion of the graph of the periodic function
f(x) = sin(1 + sinx). Find the x-coordinates of the turning points P, Q, and R. Round the answers to three decimal places. Hint: The x-coordinate of Q is halfway between the x-coordinates of P and R.

2. ## Re: Periodic Function

these are all local minima or maxima so set the derivative equal to zero an solve for x. You'll get a few solutions and you should be able to eyeball the correct ones.

3. ## Re: Periodic Function

Originally Posted by nycmath
The picture shows a portion of the graph of the periodic function
f(x) = sin(1 + sinx). Find the x-coordinates of the turning points P, Q, and R. Round the answers to three decimal places. Hint: The x-coordinate of Q is halfway between the x-coordinates of P and R.
Look at this graph.
plot sin(1+sin(x)), -2 to 6 - Wolfram|Alpha

4. ## Re: Periodic Function

Thank you everyone.

5. ## Re: Periodic Function

Hi,
I hope the attached drawing helps. In particular, 2 of the critical points (turning points) are symmetrically located about $\pi/2$.

6. ## Re: Periodic Function

Thank you, johng.