Calculating the amout of rotation on a line and the length compared to a gear I am currently working on this steam logo animation, but I got no clue how to calculate the amout of rotation and length of the first beam when attached to a gear. 
Picture: puu.sh/3okhA.jpg
In css, you can desribe the progression of a transition by supplying 2 set of coordinates which defines a bezier curve, like here: www.css3beziercurve.net/
Do anyone understand what I am saying, and is it possible to calculate this?
Here is the current state of it (might not work in older browsers, try chrome or something)
http://codepen.io/jonasroessum/pen/omtjc

If I understand correctly, what you want to know is the length and angle of your 'push-rod' so it connects to the centre of the rotating circle.
There is a simple trigonometric relationship called the law of cosines (see http://en.wikipedia.org/wiki/Law_of_cosines ) that can provide your answer. 
If the distance between the non-rotating elements is b (for base) and the length of the short rotating arm is a (for arm), and the angle between b and a is theta, then the length of your push-rod will be given by c where
 c = sqrt(a^2 + b^2 - abcos(theta)) 

Now you know c, the angle phi between b and your arm, c, will be given by 
 phi = arccos((a^2+c^2-b^2)/2ac)

Is that what you want?     
