An angular displacement of 90 degrees is equal to:
- A. One-fourth revolution
- B. One-third revolution
- C. One half revolution
- D. One complete revolution
Explanation
A full revolution is 360 degrees, so 90 degrees is a quarter of it, equivalent to pi over 2 radians. Half a revolution would be 180 degrees or pi radians. Converting between degrees, radians and revolutions is worth doing fluently, since rotational formulae require radians.