## Precalculus (6th Edition) Blitzer

If $r$ is the radius of a circle and $\theta$ is the angle subtended at the center in radians and is non-negative, then the length of the arc $s$ is given by $s=r\theta$ However, in the provided statement, the angle $\theta$ is given in degrees and $s$ is calculated by that value only. Therefore, the statement “If $r=10$ centimeters and $\theta =20{}^\circ$ , then $s=10\cdot 20=200$ centimeters” is false.