1. Description

Code a function circle_area, which takes radius as input and returns area of a circle.

The area of circle is calculated as

You can use math.pi as value of $\pi$

2. Input & Output

Input:

• A float number
• Use input() as input. Notice that the value you get from input() is a string

Output:

• Use print() for your output
• Limit the out put to two decimal points

Example

# Input: 
10.0
# Output: 
314.16

# Input: 
2.5
# Output: 
19.63