Final answer:
The police acted violently in the 1991 Rodney King beating, where officers were seen on video striking King with batons, leading to riots and discussions on police brutality.
Step-by-step explanation:
One of the ways in which the police acted violently is evidenced by the 1991 beating of Rodney King in Los Angeles, where police officers were filmed repeatedly striking an unarmed man with batons after a traffic stop. In the resulting trial, despite the clear video evidence, the involved officers were initially acquitted, leading to widespread riots and a later convicting of two officers on federal charges of using unreasonable force. This event highlights issues in policing practices and has been a focal point for discussions around police brutality and racial disparities in the United States.