Day 1: Let and Const

Objective

In this challenge, we practice declaring variables using the let and const keywords. Check out the attached tutorial for more details.

Task

1. Declare a constant variable, PI, and assign it the value Math.PI. You will not pass this challenge unless the variable is declared as a constant and named PI (uppercase).
2. Read a number, r, denoting the radius of a circle from stdin.
3. Use PI and r to calculate the area and perimeter of a circle having radius .
4. Print area as the first line of output and print perimeter as the second line of output.

Input Format

A single integer, r, denoting the radius of a circle.

Constraints

• 0 <= n <= 100
• r is a floating-point number scaled to at most 3 decimal places.

Output Format

Print the following two lines:

1. On the first line, print the area of the circle having radius r.
2. On the second line, print the perimeter of the circle having radius r.

Sample Input 0

1

2.6

##Sample Output 0

1
2

21.237166338267002
16.336281798666924

Explanation

Given the radius r = 2.6, we calculate the following:

• area = (pi*r^2)
• perimeter = ({2}pir^2)

We then print area as our first line of output and perimeter as our second line of output.

Solution

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function main() {
  // Write your code here. Read input using 'readLine()' and print output using 'console.log()'.
  let r = parseFloat(readLine());
  const PI = Math.PI;

  // Print the area of the circle:
  console.log(PI * r * r);

  // Print the perimeter of the circle:
  console.log(PI * 2 * r);

  try {
    // Attempt to redefine the value of constant variable PI
    PI = 0;
    // Attempt to print the value of PI
    console.log(PI);
  } catch (error) {
    console.error("You correctly declared 'PI' as a constant.");
  }
}