import java.awt.Polygon;

/**

* A three-sided polygon.

*/

public class Triangle extends Polygon {

/**

* Constructs a triangle at the given points.

*

* @param ax 1st x-coordinate

* @param ay 1st y-coordinate

* @param bx 2nd x-coordinate

* @param by 2nd y-coordinate

* @param cx 3rd x-coordinate

* @param cy 3rd y-coordinate

*/

public Triangle(int ax, int ay, int bx, int by, int cx, int cy) {

// check for invalid triangle

int lhs = (cy - by) * (bx - ax);

int rhs = (by - ay) * (cx - bx);

if (lhs == rhs) {

throw new IllegalArgumentException("points are collinear");

}

// store points of polygon

xpoints = new int[] {ax, bx, cx};

ypoints = new int[] {ay, by, cy};

npoints = 3;

}

/**

* @return string representation of the triangle

*/

public String toString() {

StringBuilder str = new StringBuilder();

str.append("Triangle[");

for (int i = 0; i < npoints; i++) {

if (i > 0) {

str.append(", ");

}

// append the next (x, y) point

str.append('(');

str.append(xpoints[i]);

str.append(", ");

str.append(ypoints[i]);

str.append(')');

}

str.append(']');

return str.toString();

}

}