Modify the square program to create the circle program.Make changes to the square program in order to calculate the area and circumference of a circle.a$.$ Change the comment and algorithm as neededb. Change the variable side to radiusc. Change the prompt to ask for the radius of a circle.d$.$ Keep the variables area and change the variable perimeter to circumference but change their formulas as follows:area of a circle is: $3\mathrm{.}14159*$ radius $*$ radius circumference is: $2*3\mathrm{.}14159*$ radiuse. Change the print statements to print appropriate messages.Run it$.$ Be sure you get the expected answer. If not fix error and run again until it works$\mathrm{.}3)$ Implement the algorithm for the Sales Tax problem. Ask the user to enter the input data needed and print the answer with an appropriate message$\mathrm{.}4)$ Write a program to implement the algorithm for the backyard problem. Ask the user to enter the input data needed and print the answer with an appropriate message.