Question

If a wire is bent into the shape of a square,the are of the square is 49cm^2 . When the wire is bent into a semi circular shape,find the radius of the semi circle .Take π=22/7

Answer 1

Here is ur answer
Given  : A wire is bent into the shape of a square the area of the square is 49 cm2 

Let side of square  =  x

We know area of square =  ( Side )2 , So

x2 =  49

x  = 7  cm

We know perimeter of square  =  4 (  Side ) 
So,

Perimeter of square  =  4 ( 7 ) =  28 cm

And Length of wire  =  Length of wire

So,
Length of wire  =  28 cm

As given  : The wire is bent into a semi circular shape .

So, 

Perimeter of semicircular shape  =  28 cm

We know Perimeter of semicircle  =  2πr + 2r , Here r is radius

So,
2πr + 2r = 28⇒2 × 227× r + 2r =  28⇒447× r + 2r =  28⇒r ( 447 + 2 )=  28⇒r ( 44 + 147  )=  28⇒r ( 587  )=  28⇒r = 28 × 758⇒r = 19658⇒r = 3.379 cm ≈ 3.38 cm 

Answer 2

Area of square = 81 cm²

=> Side= 9 cm

=> Perimeter = 9 x 4 = 36 cm

If this is bent into semicircle of radius r, perimeter = πr + 2r

=> r(π+ 2) = 36

You get value of r from here

A little birdie tells me r = 7 cm

Substitute this value in area formula:

Area = ½ x πr²