Chapter 3 - Radian Measure and the Unit Circle - Section 3.1 Radian Measure - 3.1 Exercises - Page 106: 92

(a) $24\pi$ radians (b) $6\pi$ radians

In one hour, the minute hand of a clock makes one full rotation, which is equivalent to $2\pi$ radians. Thus, (a) In 12 hours, the minute hand will make 12 full rotations, which is equivalent to: $=12 \times 2\pi$ $\\= 24\pi$ radians (b) In 3 hours, the minute hand will make 3 full rotations, which is equivalent to: $=3 \times 2\pi$ $\\= 6\pi$ radians