A wire is bent in the shape of a square then the area of the square is 81 sq. cm. when the wire is bent into a semicircular shape, the area of circle will be ?

  1. 22 sq. cm
  2. 44 sq. cm
  3. 77 sq. cm
  4. 154 sq. cm

take pie as 22/7
please answer with full explanation

1 Answer
Shantanu Dash
Aug 5, 2017

77 sq. cm(option 3)

Explanation:

length of each side of the square=sqrt81=9=√81=9
perimeter of the square=4*9=36=4⋅9=36
total length of the semicircle=pir+2r=r(22/7 + 2)=36r/7=πr+2r=r(227+2)=36r7
36=36r/736=36r7
r=7r=7
area of semicircle=(pir^2)/2=22/7 *49*1/2=77 sq. cm(option 3)=πr22=227⋅49⋅12=77sq.cm(option3)

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