A bike wheel is spun until it reaches an angular velocity of 2.00 rad/s. It was spun for 1.28 s. What was its change in angle during this time if it started from rest?

a = 2.00/1.28 = 1.5625 rad/s^2

so, just as distance = 1/2 at^2 in linear motion, the same rule applies here:
1/2 * 1.5625 * 1.28^2 = 1.28 radians