题解 | 点到直线距离

import java.util.Scanner;

public class Main {
    static class Point {
        double x, y;
        
        Point(double a, double b) {
            x = a;
            y = b;
        }
    }
    
    static class Line {
        Point pointA, pointB;
        Line(Point a, Point b) {
            pointA = a;
            pointB = b;
        }
    }
    static double distance(Point a,Point b) {
		double d=Math.sqrt(Math.pow(a.x-b.x, 2)+Math.pow(a.y-b.y, 2));
		return d;
	}
    static double getDistance(Point P, Line L) {
        double pa=distance(P, L.pointA);
		double ab=distance(L.pointA, L.pointB);
		double pb=distance(P, L.pointB);
		double cosA=(pa*pa+ab*ab-pb*pb)/(2*pa*ab);//余弦定理
		double sinA=Math.sqrt(1-cosA*cosA);
        return pa*sinA;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        int sx = scanner.nextInt();
        int sy = scanner.nextInt();
        int tx = scanner.nextInt();
        int ty = scanner.nextInt();
        
        Point pointA = new Point(sx, sy);
        Point pointB = new Point(tx, ty);
        Point pointC = new Point(a, b);
        Line line = new Line(pointA, pointB);
        
        System.out.printf("%.2f", getDistance(pointC, line));
        scanner.close();
    }
}

这道题主要是采用余弦定理的做法，来把点到直线距离求解