This Demonstration shows that the result of two successive rotations around different centers and under different angles is equivalent to a single rotation around a new center. In this Demonstration the angles are shown as purple and yellow arcs and the centers are locators that you can drag. The equivalent angle, equal to the sum of the angles of the rotations, is shown in orange and the new center is a brown disk.
Wolfram Demonstrations Project
Published: March 7 2011