# Arc lengths and areas

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Information about Arc lengths and areas

Published on February 18, 2014

Author: masljr

Source: slideshare.net

## Description

Geometry HIgh School, lesson, Circles, Areas, Arc Lengths, Sectors, Introduction, Perimeter, Area, Volume Unit

Mr. Saucedo Milby High School Geometry

Objective: To find partial areas and circumferences of circles.

What you should know… Find the Circumference and the Area of a circle with diameter 10.

WHAT IS? ARC LENGTH An arc length is a fraction of the circumference.

The concept… Can you find the arc length of this Semicircle? What would the arc length be if we just wanted to use a quarter of the circle?

HOW DO WE FIND ARC LENGHTS? With the following proportion: Part of a circumference Whole Circumference circle Arc length пD = Portion of degrees Whole: Degrees in a = Central Angle 360

GUIDED EXAMPLE 1 Find the length of the arc:

Independent example Find the length of the arc AB.

SECTORS What is a sector?

AREA OF A SECTOR FORMULA: AREA OF SECTOR AREA OF CIRCLE = CENTRAL ANGLE 360 AREA OF SECTOR = CENTRAL ANGLE пr2 360

GUIDED EXAMPLE 2 Find the area of the blue section

INDEPENDENT EXAMPLE Find the area of the shaded region.

HOMEWORK WORKBOOK (BLUE BOOK) Pages:

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