CODEWITHSUNDEEP
java
denominator7
denominator7

Reputation: 43

Write a program that prompts for the lengths of the sides of a triangle and reports the three angles

Write a program that prompts for the lengths of the sides of a triangle and reports the three angles.

I am not getting angles that equal to 180, and for some cases I am getting NaN for some angle values.

My code is shown below

public static int getSideA() {
    System.out.println("What is the length of side a?");
    Scanner console = new Scanner(System.in);
    int a = console.nextInt();
    return a;
}

public static int getSideB() {
    System.out.println("What is the length of side b?");
    Scanner console = new Scanner(System.in);
    int b = console.nextInt();
    return b;
}

public static int getSideC() {
    System.out.println("What is the length of side C");
    Scanner console = new Scanner(System.in);
    int c = console.nextInt();
    return c;
}

public static void giveSides(int a, int b, int c) {
    double angleA = Math.toDegrees(Math.acos((a^2 - b^2 - c^2) / (-2.0 * c * b)));
    double angleB = Math.toDegrees(Math.acos((b^2 - a^2 - c^2) / (-2.0 * a * c)));
    double angleC = Math.toDegrees(Math.acos((c^2 - a^2 - b^2) / (-2.0 * a * b)));
    System.out.println("The three angles are: " + angleA + " " + angleB + " " + angleC);
}

public static void main(String[] args) {
    int a = getSideA();
    int b = getSideB();
    int c = getSideC();
    giveSides(a, b, c);
}

Upvotes: 2

Views: 972

Answers (1)

Sweeper
Sweeper

Reputation: 270733

The problem lies in these three lines:

double angleA = Math.toDegrees(Math.acos((a^2 - b^2 - c^2) / (-2.0 * c * b)));
double angleB = Math.toDegrees(Math.acos((b^2 - a^2 - c^2) / (-2.0 * a * c)));
double angleC = Math.toDegrees(Math.acos((c^2 - a^2 - b^2) / (-2.0 * a * b)));

^2 does not mean "squared". It means "bitwise XOR 2". You need to use a*a or Math.pow(a, 2) for "a squared".

So the three lines should be:

double angleA = Math.toDegrees(Math.acos((a*a - b*b - c*c) / (-2.0 * c * b)));
double angleB = Math.toDegrees(Math.acos((b*b - a*a - c*c) / (-2.0 * a * c)));
double angleC = Math.toDegrees(Math.acos((c*c - a*a - b*b) / (-2.0 * a * b)));

Also, the getSideX methods could be combined into one and the scanner could be extracted to the class level:

static Scanner console = new Scanner(System.in);

public static int getSide(String name) {

    System.out.println("What is the length of side " + name + "?");

    int a = console.nextInt();
    return a;
}

Your main method now looks like this:

public static void main(String[] args) {

    int a = getSide("A");
    int b = getSide("B");
    int c = getSide("C");

    giveSides(a, b, c);
}

Upvotes: 4

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