Q. 203.7( 15 Votes )

Rabeya drew an equilateral triangle with sides 21 cm. on a big paper. Drawing a circle inscribing that triangle coloured the circular region. I write by calculating the area of coloured region.

Answer :


Given: Length of side of equilateral triangle = 21 cm


Area of the colored portion = Area of the circum circle - Area of ∆BCD


Height of equilateral triangle



The centroid of equilateral triangle is at A and lies on height BE.



BA = 7√3 cm


So, the radius of the circum circle of this triangle = 7√3 cm.


Area of a circle = πr2


Area of the circum circle


Area of the circum circle = 462 cm2


We know that


Area of a equilateral triangle where a is the side of it.



Area of ∆BCD = 190.96cm2


Now, Area of the colored portion = 462 – 190.96


Area of the colored portion = 271.04 cm2


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