Translations in polar coordinates

[waycoo]

Hi, I'd like to describe what I need to do visually:

In other words, I just need to translate my semi-circle (which is actually just a large circle in limited viewspace) so that it moves beyond the origin. Right now I'm using the standard formula for a circle centered at a distance r from the origin. r = -2*(a*cos(t) +b*sin(t))

Any help?

I've tried using the formula given in the last post on this page:
http://math.stackexchange.com/quest...sian-coordinate-polar-equation-and-back-again

but when I plug it into my python program, the translation gives a function which looks nothing like a circle. I'm thinking I might be entering the variables wrong.Thanks in advance,
Greg

 

[jvicens]

Hello Greg,

To visually describe your problem, imagine a coordinate system with the origin at the center. The semi-circle is represented as a large circle with its center at a distance r from the origin. The formula you are using, r = -2*(a*cos(t) +b*sin(t)), represents a circle with a radius of r and its center at (a,b).

To move this circle beyond the origin, you can use the formula r = -2*(a*cos(t) +b*sin(t)) + c, where c represents the distance you want to move the circle. This will shift the entire circle by c units in the desired direction.

In terms of your python program, make sure you are using the correct variables for the formula. The variable a represents the horizontal distance from the origin, while b represents the vertical distance. The variable c represents the distance you want to move the circle.

I hope this helps! Let me know if you have any further questions. Good luck with your project!