A reflection is an image that is flipped over a line and the new image is equidistant from the pre-image. The line of reflection itself is an angle bisector to the reflection. The two images that are reflected are the same direction and distance away from the line on either side. A reflection of yourself would be like looking on a mirror. To do my reflection i plotted one point and to find the other point you change the first coordinates based on what line you are reflecting over, for example point (3,2) reflected over the Y axis would change to (-3,2) because you are changing from quadrant one to 2 and to do so you must negate the X coordinate.