The perimeter of a certain sector of a circle is 20cm . If the radius of circle is 6 cm , then find the area of the sector . How to solve this ? Is there any formula for this which is out of NCERT maths TB ? Plz help !

A sector is made up of two radius and one arc.
As the radius is given as  6 cm, and the perimeter is 20cm
So the arc length will be 20 - 6- 6 = 8cm

Circumference of a circle is given by 2 πr
So the circumference is 2*π*r = 12π

As 12π subtend 360 degree at the centre
So 8cm will subtend (360/12π )* 8 = 240/π
So the angle subtended by given arc will be 240/π

And the area of the circle is πr2 = π(6)2
It is the area of full circle, it means 360 degree has area of 36π
As 360 degree = 36π
So for 240/π degree the area will be = (36π/360)*(240/π) = 24cm2
So the area of the sector is 24cm2


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hey, this is simple, a sector is made of 2 radii and one arc, so perimeter of sector is 2r + length of arc, now by knowing the length of arc, you can find your angle and use it for area, see in this sum, 2r + length of arc = 20 cm = 2(6) + arc length = 20 cm and you get arc of length equal to 8 cm. now apply formula and find angle.

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