# Copy of Introduction to Radian Measure

Target: Given a circle's radius and an arc measure, find the arc length.

*Arc Length – A portion of the circumference of the circle.*Drag the “Arc” slider. 1) How does the arc length of a semicircle compare with the Circumference? 2) How does the arc length of a whole circle compare with the Circumference?

*Radian - a unit of measure, equal to an angle at the center of a circle whose arc length is equal in length to the radius.*3) Drag the “Arc” slider to 1. How does the arc length compare with the radius? 4) Drag the “Arc” slider to 4. How does the arc length compare with the radius? 5) How many radians are in a semicircle with radius = 1 unit? 6) How many radians are in a circle with radius = 1 unit? 7) Drag the “Radius” slider to 2. How many radians are in a semicircle with radius = 2 units? 8) How many radians are in a circle with radius = 2 units? 9) Drag the “Arc” slider to 1. What is the arc length with an arc measure of 1 radian in a circle with radius 2 units? 10) What is the arc length of an arc with a measure of 3 radians in a circle with radius 2 units? 11) What is the arc length of an arc with a measure of 5 radians in a circle with radius 2 units? 12) What is the arc length of an arc with a measure of 5 radians in a circle with radius 5 units?

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