program:

#to find the radius of the circle

r=float(input("input the radius of the circle:"))
a=(22*r*r)/7
print("the area of circle with radius",r,"is:",a)

output:

input the radius of the circle:1.1
the area of circle with radius 1.1 is: 3.8028571428571434

program:

#to find the extension of the file

a=input("Input the Filename: ")
b=a.split(".")
c=print ("The extension of the file is : " ,b[-1])


output:

Input the Filename: abc.py
The extension of the file is :  py
