How to Find a Triangle Within a Triangle Using Java Code

By calculating the midpoint of the sides of a triangle, you can connect those midpoints to determine smaller sub-triangles. You accomplish this in Java by beginning with the three coordinates of a triangle, calculating the differences of those coordinates to find the midpoints of all the sides, and then constructing a new triangle out of those midpoints.

Things You'll Need

• Java Development Kit

Instructions

1. Create a class that represents a triangle, storing three points representing x and y coordinates. These points will represent the basic triangle (Source 1):

   class T{

   public static void main(String[] args){

   int[] s1 = {10, 6};
   int[] s2 = {16, 16};
   int[] s3 = {4, 0};

   }
   }

2. Determine the midpoint of two different sides (Source 1):

   int diff_side1x = s2[0] - s1[0];
   int diff_side1y = s2[1] - s1[1];
   int[] mid_side1 = {diff_side1x + s1[0], diff_side1y + s1[1]};

   int diff_side2x = s2[0] - s3[0];
   int diff_side2y = s2[1] - s3[1];
   int[] mid_side2 = {diff_side2x + s3[0], diff_side2y + s3[1]};

3. Connect the two midpoints to one of the already existing points. These three points will form a triangle inscribed in the original (Source 1):

   //original triangle
   s1;
   s2;
   s3;

   //internal triangle
   s3;
   mid_side1;
   mid_side2;

   //internal triangle
   s2;
   mid_side1;
   mid_side2;

References

• Wolfram Mathworld: Triangle