curves eq. mathematica

• May 25th 2010, 09:42 AM
acied
curves eq. mathematica
how to find the curve parametric equations from the given graph in mathematica 7??

the graph in the attach file, and its name Cycloid

Cycloid - Wikipedia, the free encyclopedia
• May 25th 2010, 01:59 PM
galactus
The parametric equations for a cycloid are given by

$x=a{\phi}-a\cdot sin{\phi}, \;\ y=a-a\cdot cos{\phi}$

Where 'a' is the radius of the circle.

To plot in Mathematica, maybe let a=1 or some other arbitrary value.

I let a=1 here, and the range can be whatever. I just used 4 Pi to show 2 'rolls'.

ParametricPlot[{u-Sin[u],1-Cos[u]},{u,0,4Pi}]

Does this help?
• May 25th 2010, 03:51 PM
acied
but how can i get the curve equation from the data which is in the graph??