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Given the following text description, write Python code to implement the functionality described.
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Description:
Area of largest Circle that can be inscribed in a SemiCircle
Function to find the area of the circle ; Radius cannot be negative ; Area of the largest circle ; Driver code

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Python Code:
def circlearea(R ) : 
	 if(R < 0 ) : 
	 return - 1 ; 
  a =(3.14 * R * R ) / 4 ; 
 return a ; 
  if __name__== "__main __": 
	 R = 2 ; 
 print(circlearea(R ) ) ; 
 
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