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pi – Circumference and Area

Given the radius of a circle, calculate its circumference and area.

diagram showing the circumference and area of a circle

The circumference of a circle with radius r is given by 2 × π × r or two times pi times the radius.

The area of a circle with radius r is given by π × r ² or pi times the square of the radius.

The number π, or pi, is a mathematical constant with an irrational value of 3.141 592 653 …

Input and Output

Each line of input contains a decimal value r indicating the radius.

0 < r < 10000.0

For each line of input, your program should produce two numbers, c and a indicating the circumference and area. They should be rounded to two decimal places.

Example input


Example output

6.28 3.14
75.40 452.39
41.47 136.85
1.00 0.08

Functions circumference and area

To reach a full score your program should implement two functions circumference and area. Each should take a double-precision floating point number and return a double-precision floating point number. Please see the information for your programming language of choice:



  1. The value of π (pi). The value of π (pi) is a real number so the only way to represent it as a floating point value is to use an approximation. Although you can use a hardcoded value of 3.141592653589793 for π it is better to use the one provided by your programming language of choice:

    • in C, use M_PI from math.h;
    • in Python, use pi from the math module (a.k.a.: math.pi);
    • in Haskell use pi from the Prelude.

try first: mult

try next: oddeven order

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