One time I was drawing a portrait of myself. At first, I have trouble sketching out the picture. The left and the right side of my face don't balance out. But because I LOVE math, I applies the concept of symmetry into my drawing. On a 11x8 in. graphing paper, (using a ruler) I draw a symmetry line (The paper has two lines of symmetry). What I did is divide my paper into four congruent squares. I start by drawing the right side of my face, and using the concept of reflection/proportion, I am able to work it through. For example, if the right side of my lip ends at the coordinate (3,2) then the left side have to ends at (-3,-2).