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An arc of a circle is of length 5p cm and the sector bounds an . . .

Question : An arc of a circle is of length 5p cm and the sector bounds an area of 20p cm². Then, the radius of the circle is
(a) 4 cm 
(b) 8 cm 
(c) 12 cm 
(d) 16 cm

Doubt by Shravya

Solution : 

Length of arc = 5p cm
Area of sector = 
20p cm²
Radius  = ?

Formula Used
Area of sector = ½×length of arc × Radius
2 [Area of sector / length of arc] = Radius
Radius = 
2 [Area of sector / length of arc] 
Radius = 2[
20p/5p]
Radius = 40p/5p
Radius = 8 cm 

Hence, (b) 8 cm, would be the correct option. 

Similar Question : 

1.) An arc of a circle is of length 5π cm and the sector bounds an area of 20π cm². Then, the radius of the circle is
(a) 4 cm 
(b) 8 cm 
(c) 12 cm 
(d) 16 cm

2.) Area of sector of a circle of radius 36 cm is 54π cm². Find the length of the corresponding arc of the sector. [3π cm]

3.) The length of an arc of a circle is 4 cm and its radius is 6 cm. Find the area of this sector of the circle. [12 cm²]