# Math Help - Circular function

1. ## Circular function

How would you go about finding the figures to sketch a circular function?

Thanks
James

2. ## Re: Circular function

I'd start by remembering that $\displaystyle \cos{ \left( X + \pi \right) } = -\cos{(X)}$.

3. ## Re: Circular function

see the figure below
the rest is easy

4. ## Re: Circular function

Minoanman,

I haven't a clue as to what curve you have drawn. Could you be more explicit by giving parametric equations or an implicit equation for the curve? In what sense does your curve represent
$y=1-2\text{cos}(3\theta+\pi)$?

5. ## Re: Circular function

f(θ)=y=1-2cos(3θ+π) .............this is the curve as supplied by James .......read the second line of his POST...

if you substitute θ ith x you will get .

if you substitute y for r ( Polar forms) then you will get..

6. ## Re: Circular function

Minoan,
But what is the curve of your first response?

7. ## Re: Circular function

y=1-2cos(3θ+π) as given by James....

8. ## Re: Circular function

Minoan,
I'll try to make my question perfectly clear. Presumably, you used some software to generate the image in your first response. What was the software and exactly what did you type to get the curve?

Neither Geogebra nor Graph will accept the given equation: y=1-2cos(t+pi) (or theta for t). Wolfram Alpha interprets the given equation as plotting the function y=f(t) with parameter t; that is, the first graph of your second response.