the reference answer GPT ᴼ ᴾ ᴱ ᴺ ᴬ ᴵ < br / > is a Python implementation code below:
import math r = float(input("Please enter radius:")) circumference = 2 * math.pi * r round_area = math.pi * r ** 2 print("Circumference is %.2f" % circumference) print("Round area is %.2f" % round_area)
First, we use the input() function to take the user's input radius value and convert it to a floating-point number type. We then use the pi constant from the math library to calculate the circumference and the circle area and assign the results to the variables circumference and round_area, respectively.
Finally, we format the output as a string, leaving two decimal places for the circumference and area of the circle. Where %.2f means to output a floating-point number and keep two decimal places.