Centre and radius of a circle passing through 3 points in a plane: Difference between revisions

=={{header|Java}}==

<syntaxhighlight lang="java">

public final class CentreAndRadiusOfACirclePassingThrough3PointsInAPlane {

public static void main(String[] args) {

Circle circle = computeCircle( new Point(22.83, 2.07), new Point(14.39, 30.24), new Point(33.65, 17.31) );

System.out.println(circle);

}

private static Circle computeCircle(Point pointOne, Point pointTwo, Point pointThree) {

double centreX = 0.5 *

(

( pointOne.x * pointOne.x + pointOne.y * pointOne.y ) * ( pointThree.y - pointTwo.y ) +

( pointTwo.x * pointTwo.x + pointTwo.y * pointTwo.y ) * ( pointOne.y - pointThree.y ) +

( pointThree.x * pointThree.x + pointThree.y * pointThree.y ) * ( pointTwo.y - pointOne.y )

)

/

(

pointOne.x * ( pointThree.y - pointTwo.y ) +

pointTwo.x * ( pointOne.y - pointThree.y ) +

pointThree.x * ( pointTwo.y - pointOne.y )

);

double centreY = 0.5 *

(

( pointOne.x * pointOne.x + pointOne.y * pointOne.y ) * ( pointThree.x - pointTwo.x ) +

( pointTwo.x * pointTwo.x + pointTwo.y * pointTwo.y ) * ( pointOne.x - pointThree.x ) +

( pointThree.x * pointThree.x + pointThree.y * pointThree.y ) * ( pointTwo.x - pointOne.x )

)

/

(

pointOne.y * ( pointThree.x - pointTwo.x ) +

pointTwo.y * ( pointOne.x - pointThree.x ) +

pointThree.y * ( pointTwo.x - pointOne.x )

);

double radius = Math.sqrt( ( centreX - pointOne.x ) * ( centreX - pointOne.x ) +

( centreY - pointOne.y ) * ( centreY - pointOne.y ) );

return new Circle( new Point(centreX, centreY), radius);

}

private static record Circle(Point centre, double radius) {

public String toString() {

return "centre: (" + format(centre.x) + ", " + format(centre.y) + "), radius = " + format(radius);

}

private String format(double value) {

return String.format("%.5f", value);

}

}

private static record Point(double x, double y) {}

}

</syntaxhighlight>

{{ out }}

<pre>

centre: (18.97852, 16.26541), radius = 14.70862

</pre>