Page 4 - Lesson Note

P = 24 + 2 π

P = 24 + 6.28 = 30.28

Hence, Perimeter of sector is 30.28 cm

Example 3- A sector is cut from a circle of radius 21 cm. The angle of the sector
o
is 150 . Find the length of its arc and area.
Solution- The length of arc l and area A of a sector of angle θ in a circle of radius r are
given by,

= × 2
360°
and

2
= ×
360°
respectively.

Here, r = 21 cm and θ = 150°

150 22
∴ × 2 × × 21 = 55
360 7

150 22 1155
2
= × × 21 × 21 = = 577.5 cm
360 7 2

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