### Question:
Vector3D { public static float distanceVertices(float[] left, float[] right) { float sum = 0; for (int i = 0; i < 3; i++) { sum += (left[i] - right[i])*(left[i] - right[i]); } return (float) Math.sqrt(sum); }  static float[] vectorMultiply(float[] lhs, float[] rhs); static float scalarMultiply(float[] lhs, float[] rhs); static float distanceVertices(float[] left, float[] right); static float vectorLength(float[] vector); static float[] createVector(float[] start, float[] end); static float distanceDotLine(float[] dot, float[] lineA, float[] lineB); static float distancevertexSegment(float[] dot, float[] segmentStart, float[] segmentEnd); static final float Epsilon; }### Answer:
@Test public void distanceVertices() throws Exception { float[] start = {0, 1, 0, 1}; float[] end = {5, 1, 0, 1}; float[] vertex = {3, 0, 0, 1}; float res = Vector3D.distanceVertices(start, end); assertTrue(equal(res, 5)); res = Vector3D.distanceVertices(start, vertex); assertTrue(equal(res, 3.1623f)); }