编辑代码

import java.lang.Math;

public class MyTriangle {
    public static double area(double a, double b, double c) {
        if (!isValid(a, b, c)) {
            return -1;
        }
        return Math.sqrt((a + b + c) / 2 * (-a + b + c) / 2 * (a - b + c) / 2 * (a + b - c) / 2);
    }

    public static boolean isValid(double a, double b, double c) {
        if ((a + b) > c && (a + c) > b && (b + c) > a && a > 0 && b > 0 && c > 0) {
            return true;
        }
        return false;
    }

    public static double area(double bottom, double height) {
        return 0.5 * bottom * height;
    }

    public static double area(double a, double b, int angleOfAandB) {
        double sin = Math.sin(angleOfAandB / 180 * Math.PI);
        return 0.5 * a * b * sin;
    }

    public static double perimeter(double a, double b, double c) {
        if (!isValid(a, b, c)) {
            return -1;
        }
        return a + b + c;
    }

    public static void main(String[] args) {
        System.out.println(isValid(3.5, 4, -1));
        System.out.println(isValid(3, 4, 5));
        System.out.println(isValid(1, 2, 2));
        System.out.println(area(0, 4.5, 5.5));
        System.out.println(area(3.5, 4.5, 5.5));
        System.out.println(Math.sin(180));
        System.out.println(area(3, 6));
    }
}