public class Triangle implements Shape {
	private double a, b, c;
	
	public Triangle(double a, double b, double c) {
		this.a = a;
		this.b = b;
		this.c = c;
	}
	
	public double area() {
		double s = 0.5 * (a + b + c);
		return Math.sqrt(s * (s - a) * (s - b) * (s - c));
	}
	
	public double perimeter() {
		return a + b + c;
	}
}