Course: Trigonometry
Topic: Circular Functions
Subtopic: Arc Length & Area of a Sector


This lesson is dedicated to two important circle formulas, the length of an arc of a circle (`s = r theta`) and the area of a sector of a disk (`A = 1/2 r^2 theta`). These will enable us to extend our ability to solve application problems.


By the end of this topic you should know and be prepared to be tested on:


Terms you should be able to define: arc, circle vs. disk, central angle, subtends, arc length, sector of a disk

Mini-Lectures and Examples

STUDY: Radian Measure & Arc Length & Area of a Sector

Supplementary Resources (recommended)

READ THIS ARTICLE Radian Angular Measure which is an excerpt from Trigonometric Delights by Eli Maor, Princeton University Press, 1998. The article answers such questions as, "Why are there 360 degrees in a circle?", "Why are angles measured counterclockwise?", and "Why use radians over degrees?". Math majors are definitely encouraged to read the entire book (and everything else my Eli Maor, in my opinion).

Supplemental Resources (optional)

Videos: Arc Length and Area of a Sector
Examples:  Arc Length and Application of Arc Length
Examples:  Area of a Sector and Area Bounded by a Chord and Arc

rev. 2020-10-10