Areas Related to Circles — Part 1: Sectors and arcs: visual lesson, CBSE Class 10 Mathematics (Standard 041 / Basic 241)

Lesson

Areas Related to Circles, Part 1: Sectors and arcs

A slice of a circle is just a fraction of the whole.

In this lesson you will

Recognise sectors, arcs, minor and major parts of a circle
Find the area of a sector and the length of its arc for any angle
Find the perimeter of a sector
Work backwards from an arc or an area to the angle or radius
Solve clock, pendulum and sports-ground problems

A **sector** is the region between two radii and the arc they cut off.

Concept

What you will be able to do

Name sectors and arcs, minor and major
Find the area of a sector
Find the length of an arc and the perimeter of a sector
Work backwards to an angle or a radius
Use the value of $\pi$ the question gives

Diagram

Parts of a circle

Minor sector (shaded) and major sector: their angles add up to $360^\circ$.

Two radii cut a circle into a minor sector and a major sector; their arcs are the minor and major arcs. The two angles at the centre add up to $360^\circ$ .

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