The Sum of Two Counter-Rotating Circular Vectors Is an Ellipse
The two vectors and their sum are shown as black, blue, and red, respectively. You can change the size of the blue vector relative to the black vector; both vectors rotate at the same rate but in opposite directions.
"The Sum of Two Counter-Rotating Circular Vectors Is an Ellipse"
Wolfram Demonstrations Project
Published: August 22 2013