java—从三个侧面计算的Angular 只能显示90度或180度

utugiqy6 于 2021-06-30 发布在 Java

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这个问题在这里已经有答案了：

整数除法：为什么1/3的结果==0(（16个答案）
24天前关门。
这就是问题所在：编写一个程序，提示输入三角形边的长度，并报告三个Angular 。
我为此编写了以下代码：

public static void main(String[] args) {

    Scanner console = new Scanner(System.in);

    System.out.print("Please input length of side A: ");
    int sideA = console.nextInt();
    System.out.print("Please input length of side B: ");
    int sideB = console.nextInt();
    System.out.print("Please input length of side C: ");
    int sideC = console.nextInt();
    System.out.println();
    System.out.println("The angle between A and B is: " + calculateAngle(sideA, sideB, sideC));
    System.out.println("The angle between B and C is: " + calculateAngle(sideB, sideC, sideA));
    System.out.println("The angle between C and A is: " + calculateAngle(sideC, sideA, sideB));     
}

    public static double calculateAngle(int a, int b, int c) {
        return Math.toDegrees(Math.acos((a * a + b * b - c * c) / (2 * a * b)));
    }

下面是我上面代码的输出示例：

Please input length of side A: 55
Please input length of side B: 22
Please input length of side C: 76

The angle between A and B is: 90.0
The angle between B and C is: 90.0
The angle between C and A is: 90.0

无论我为边输入什么值，我得到的唯一Angular 都是90度或180度，而不是可以根据余弦规则计算出的实际正确Angular 。我的代码怎么了？

Java

来源：https://stackoverflow.com/questions/65276333/calculated-angles-from-three-sides-only-show-either-90-or-180-degrees

2条答案

按热度按时间

cunj1qz11#

算了算就行了 Math.acos 至 double :

return Math.toDegrees(Math.acos((double)(a * a + b * b - c * c) / (2 * a * b)));

正如您在注解中看到的，当在多个 int 类型 integer 使用算术，然后将其转换为 double .
同样值得注意的是 int 总是四舍五入，意思是：

int i = 0.9999999;  // i = 0

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ux6nzvsh2#

根据文档，他们期望一个双精度值作为他们的参数 acos 方法javase7 math doc
所以像这样重新排列你的代码

public static void main(String[] args) {

        Scanner console = new Scanner(System.in);

        System.out.print("Please input length of side A: ");
        double sideA = console.nextDouble();
                System.out.print("Please input length of side B: ");
        double sideB = console.nextDouble();
        System.out.print("Please input length of side C: ");
        double sideC = console.nextDouble();
        System.out.println();
        System.out.println("The angle between A and B is: " + calculateAngle(sideA, sideB, sideC));
        System.out.println("The angle between B and C is: " + calculateAngle(sideB, sideC, sideA));
        System.out.println("The angle between C and A is: " + calculateAngle(sideC, sideA, sideB));
    }

    public static double calculateAngle(double a, double b, double c) {
        return Math.toDegrees(Math.acos((a * a + b * b - c * c) / (2 * a * b)));
    }

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java—从三个侧面计算的Angular 只能显示90度或180度

2条答案

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