# Length of an Arc

Construct the point B' on the circle c so that the size of an angle BAB' is 76°.

## Hint

Use tool for construction an angle with given size. To measure arc length use circular arc .

The length of an arc of a circle with radius 3 cm if the arc subtends a central angle of 72° is

Let *r* is radius of the circle and a is central angle. Write the formula for arc length *BB'*.