⇒ a =  π  r =  3.14  r = 1.57r 
2  2 
⇒  r_{1}  =  2 
r_{2}  3 
=  (  r_{1}  )  ^{2}  =  (  2  )  ^{2}  = 4 : 9 
r_{2}  3 
a =  a  . 

∴ r =  a  . 

⇒ π  (  a  )  ^{2}  = 154 

⇒  (  a  )  ^{2}  =  154  =  154 × 7  = (7)^{2} 

π  22 
If the area of a circle is equal to the area of square with side 2  π  units, then what is the diameter of the circle ? 
⇒ x = 5 and  –15 
2 