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S = contains supplemental resources
Course: Trigonometry
Topic: Circular Functions
Subtopic: Arc Length & Area of a Sector

Overview

This lesson is dedicated to two important circle formulas, the length of an arc of a circle (s=rθ) and the area of a sector of a disk (A=½r2θ). These will enable us to extend our ability to solve application problems.

Objectives

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

Terminology

Define: arc, circle vs. disk, central angle, subtends, arc length, sector of a disk

Supplementary Resources

Read 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 free online (and everything else my Eli Maor, in my opinion). It's a fun read!