Explore radian measure by following these steps.

✓ 1. Move point K to set m∠JPK to 1 radian. What is the relationship between the radius r and the arc length? r < s r = s r > s

✓ 2. Move point K to set m∠JPK to 2 radians.
What is the relationship between the radius r and the arc length? s = r s = 2r r = 2s

✓ 3. What is the relationship between the radius and arc length when the central angle is a semicircle? s = r s = 2r s = 3.14r

✓ 4. If the central angle is measured in radians, what is the relationship between the radius r, arc length s, and central angle θ? s = r s = θr s = πr