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Question:
a wire when bent in the form of an equilateral triangle encloses an area of 121x1.73 sq.cm.If the same wire is bent in the form of a circle,find the area of the circle
Answer:

Let the side of the equilateral triangle = a

Noe area of the triangle = (√3/4)a2

Now (√3/4)a2 = 121*1.73

=> (1.73*a2 )/4 = 121*1.73              (since √3 = 1.73 )

=> a2 /4 = 121

=> a2 = 121*4

=> a = √(121*4)

=> a = 11*2

=> a = 22

Total length of the wire = 3a     (since there are 3 sides in a traingle)

                                    = 3*22

                                    = 66 

Now this wire is bent into circle.

Let radius of the circle is r.

So circumference of circle = 66

=> 2*Π*r = 66

=> (2*22*r)/7 = 66

=> 2*22*r = 66*7

=> r = (66*7)/(2*22)

=> r = (6*7)/(2*2)

=> r = (3*7)/2

=> r = 21/2

Now area of the circle = Π*r2

                                  = (22/7)*(21/2)2

                                  = (22*21*21)/(7*2*2)

                                  = (11*21*21)/(7*2)

                                  = (11*21*3)/2

                                  = 693/2

                                  = 346.5 cm2

So are of the circle is 346.5 cm2

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