Unit 7: Trigonometry Name ________________________ Lesson 3 – Length of an Arc; Area of a Sector Length of an Arc is simply the length of its portion of the circumference. The length of an arc is traditionally symbolized by the letter “s” and measured in radians. **If you are given the angle in degrees, you must convert angle to radian measure prior to substituting into formula.**

Radians: 22

s rT SS

x or just s rT

Area of a sector of a circle:

Radians: 2

2A rT S

S x or 21

2A rT

7)

Practice – Complete all problems on a separate sheet. No work, no credit.

II. Given the degree measure of a central angle, find the length of its intercepted arc in terms of pi in a circle of diameter 60 in.

III. Given the length of the arc, find the degree measure of the central angle it subtends to the nearest tenth of a degree if the radius of the circle is 16 cm.