Round #649

What is the area of a circle with radius 5? Use pi approximately 3.14159.

To calculate the area of a circle, you can use the formula: \[ \text{Area} = \pi \times r^2 \] where \( r \) is the radius of the circle. Given: - Radius (\( r \)) = 5 - Pi (\( \pi \)) ≈ 3.14159 Substitute these values into the formula: \[ \text{Area} = 3.14159 \times (5)^2 \] First, calculate \( 5^2 \): \[ 5^2 = 25 \] Now multiply by pi: \[ \text{Area} = 3.14159 \times 25 \] \[ \text{Area} = 78.53975 \] So, the area of a circle with radius 5 is approximately **78.54** square units (rounded to two decimal places).

To calculate the area of a circle given its radius and using an approximation for π, you can use the formula: \[ \text{Area} = \pi \times r^2 \] Here's how you can implement this in C#: ```csharp using System; class Program { static void Main() { double radius = 5; double pi = 3.14159; try { double area = CalculateCircleArea(radius, pi); Console.WriteLine($"The area of the circle with radius {radius} is {area:F2}"); } catch (Exception ex) { Console.WriteLine($"An error occurred: {ex.Message}"); } } static double CalculateCircleArea(double radius, double pi) { if (radius < 0) { throw new ArgumentException("Radius cannot be negative.", nameof(radius)); } return pi * Math.Pow(radius, 2); } } ``` ### Explanation: 1. **Main Method**: - The `Main` method is the entry point of the program. - It initializes the radius and π values. - It calls the `CalculateCircleArea` method to compute the area. - It handles any exceptions that might occur during the calculation. 2. **CalculateCircleArea Method**: - This method takes two parameters: `radius` and `pi`. - It first checks if the radius is negative and throws an `ArgumentException` if it is, as a circle's radius cannot be negative. - It then calculates the area using the formula \( \text{Area} = \pi \times r^2 \) and returns the result. 3. **Error Handling**: - The program includes basic error handling to catch any exceptions that might occur during the calculation and print an error message. This implementation is straightforward and follows best practices for C# programming, including proper error handling and clear method separation.