Tammy is at the dentist's office waiting on her appointment. she notices that the 6-inch-long minute hand is rotating around the clock and marking off time like degrees on a unit circle. part 1: how many radians does the minute hand move from 1: 20 to 1: 55? (hint: find the number of degrees per minute first.)

There are 12 five minutes in one hour and 1 hour correspond to 360°, then each 5 minutes represents 360/12 = 30°

From 1:20 to 1: 55 we have 35 minutes or 7 x 5 minutes or

7 x 30° = 210° 

To convert degree into radian, we apply the following formula:

degree/180° = radian/π

210/180 = r/π or (cross multiplication) →Radian = (π x 210/180

→ Radian = 7π/6 (simplify by 30)