Java Program to find area of different shapes using inheritance

Program

import java.util.*;
interface AreaPerimeter
{
    float calculateArea(float x, float y);
    float calculatePerimeter(float a, float b);   
}
class Rectangle implements AreaPerimeter
{
    public float calculateArea(float x, float y)
    {
        float area = x * y;
        return area;
    }
    public float calculatePerimeter(float a, float b)
    {
        float perimeter = (2 * a) + (2 * b);
        return perimeter;
    }
}
class Triangle implements AreaPerimeter
{
    public float calculateArea(float x, float y)
    {
        float area = (float) 0.5 * x * y;
        return area;
    }
    public float calculatePerimeter(float a, float b)
    {
        float perimeter = 2 * (float) Math.PI * a;
        return perimeter;
    }
}
public class FindAreaInheritance
{
    public static void main(String[] args)
    {
        float area, perimeter;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter value of a:");
        float a = sc.nextFloat();
        System.out.println("Enter value of b:");
        float b = sc.nextFloat();
        Rectangle rect = new Rectangle();
        area = rect.calculateArea(a, b);
        perimeter = rect.calculatePerimeter(a, b);
        System.out.println("Rectangle");
        System.out.println("Area:\t" + area);
        System.out.println("Perimeter:\t" + perimeter);
        Triangle triangle = new Triangle();
        area = triangle.calculateArea(a, b);
        perimeter = triangle.calculatePerimeter(a, b);
        System.out.println("Triangle");
        System.out.println("Area:\t" + area);
        System.out.println("Perimeter:\t" + perimeter);
        sc.close();
    }
}

Output

Enter value of a:
5
Enter value of b:
8
Rectangle
Area:   40.0
Perimeter:      26.0
Triangle
Area:   20.0
Perimeter:      31.415928