Rotate A Circle About A Circle

[gailplush]

I have a five inch circle, with the point (for simplicity) (3,4). Now, I want to offset that circle by (1,1). Making my new point (4,5). That seems simple enough. If I rotate the offset circle around the original circle, I would like to be able to calculate the new point. In my example the point was rotated up ~53 degrees from the X axis. If I rotate it to 60 degrees, where would it be? This has me puzzled. I've come up with a few things, but they don't pan out, when I test it in CAD.


Thanks for any help,

GP

 

[mmm4444bot]

rotate the offset circle around the original circle What does this mean?

Are you trying to say that, as the shifted circle rotates around the other, the center of the shifted circle traces out a unit circle centered at the Origin?

 

[gailplush]

That is correct. So, I know a point on my original circle, located at the origin, and I know from the shift value where the new point is. I don't know how to translate it when I rotate the offset circle from the origin. I guess you could look at it, as rotating both circles, since the original, at the origin wont change.

Let me know if I need to clear anything else up.

gP

 

[mmm4444bot]

Are you using an angle in standard position, to state the amount of "rotation"?

 

[gailplush]

I think I understand the question. I'm using the angle of the vector starting from to the origin, pointing to the original point (circle located on the origin).

Thanks,

GP

 

[gailplush]

Looking at my response, I think that is more confusing. I think this image will help....

 

[gailplush]

Thanks...I figured it out. The problem wasn't calculating the new point. I was calculating the point when rotated. Obviously, I could go into cad then shift the point, but I needed it to be dynamic. The piece I was missing, is that the new point creates a new angle to the origin. That seems insanely obvious now.

Thanks again,

GP