Returns a triangle
| x1 | x-coordinate of the first vertex |
| y1 | y-coordinate of the first vertex |
| x2 | x-coordinate of the second vertex |
| y2 | y-coordinate of the second vertex |
| x3 | x-coordinate of the third vertex |
| y3 | y-coordinate of the third vertex |
Example:
shape = triangle(30, 75, 58, 20, 86, 75) shape.draw(1, 1000)