# Arc Length

## Arc Length

1. Construct a circle with center and radius.
2. Construct a circular sector. Be sure to select the center first (point A), then select two points on the circle (B and C). Make sure the arc is less than 180 degrees (minor arc).
3. Measure the central angle by selecting the angle feature from the top menu, then highlighting the three points. The center point must be selected second.

## Circumference.

1. Measure the length of the radius from your circle by selecting distance or length from the top menu, then selecting the two endpoints of a radius. Record your answer. 2. Calculate the circumference of the circle. Record your answer.

Arc length is the distance along an arc of a circle. It is part of its total circumference. To calculate arc length, you multiply the circumference by the central angle measure divided by 360 degrees.

Calculate the arc length of the arc you constructed. Use the formula given.

Use the circle feature in the top menu to construct a circular arc. To do so, select the center point followed by the two points on the circle. The arc should be bold. Now measure the length of the arc you just constructed by selecting distance or length from the top menu, then clicking on the arc. How does this length compare with the length you calculated using the formula?