求面积

[java]代码库

package Y_S;

import java.util.Scanner;

class A {
	double r;
	double a, b, c;

	double circle() {
		// 圆面积
		double S = 3.14 * this.r * this.r;
		return S;
	}

	double triangle() {
		// 三角形面积
		double p = (a + b + c) / 2;
		double S = Math.sqrt(p * (p - a) * (p - b) * (p - c));
		return S;
	}
	
}

public class F {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		System.out.printf("输入圆的半径：\n");
		double R = input.nextInt();
		A a = new A();
		a.r = R;
		double s1 = a.circle();
		System.out.printf("圆的面积是：%f\n", s1);
		System.out.printf("输入三角形的边长：\n");
		double A = input.nextInt(), B = input.nextInt(), C = input.nextInt();
		a.a = A;
		a.b = B;
		a.c = C;
		double s2 = a.triangle();
		System.out.printf("三角形的面积是：%f", s2);
	}
}