What is the inverse of a rotation by any angle around the point O?[br][br]Drag the first slider to rotate triangle ABC.[br]Then drag the second slider to rotate the image A'B'C' by the angle beta until it coincides with ABC. What is the measure of beta?[br][br]Finally, drag the last slider until the image coincides with triangle ABC. What is the measure of delta? [br][br]Inverses are unique and "undo" the original rotation. The inverse of alpha is its opposite, or delta.