Creating kinematic movement might seem extremely difficult.  Results are often wowing and sexy; heres an example I did a few years ago. Some people think that this type of animation is reserved to the elite of the flash programming world. In reality the law of cosines formula is quite simple and easy to implement.

here it goes : a2 = b2 + c2 - 2bc cos A

yup the a2 means "a squared" ... sorry my css is not made for this type of stuff.

also if A = 90 degrees, then cos 90 = 0, and the equation reduces to the Pythagorean Theorem : a2 = b2 + c2.

All things said its a simple formula to calculate 1 angles we need in order to rotate our elements.  If you are still having trouble, check out this swf and go through my script bellow.