Question

An arc of length 20 cm subtends an angle of 144° at centre of circle. Find the radius of the circle.

Answer 1

Length of arc = 20π cm

Let radius = ‘r’ cm

O = angle subtended at centre = 144°

length of arc=picture

Answer 2

Answer:

The radius of the circle is 25 cm .  

Step-by-step explanation:

MISTAKE IN THE QUESTION , An arc of length IS 20π  cm

Given :  

Length of Arc, l = 20π cm

Angle subtended by an Arc , θ = 144°

Length of Arc, l = (θ/360) × 2πr

20π = (144°/360°) × 2× π × r

20 = (144°/360°) × 2r

20 = (12/30) × 2r

20 = (⅖)× 2r

20 × 5 = 4r

r = 100/4

r = 25 cm  

Radius of the circle, r = 25 cm

Hence,the radius of the circle is 25 cm .  

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