imagine an object revolving about some point it might be a wheel a line of hand holding skaters, or a string of beads as in fig. 8.2. Whirled in a circle, each bead sails along a different arc, but each sweeps through the same angle ๑. until now, we've measured angles in degress, 360 to a circle. yet, there is nothing special about degrees they are a remnant of the ancient Babylonian number system, whose base was 60 rather than 10.