I use the fine tip of the pencil with light pressure to fill in my front hairs, and longer side of the triangle for thicker strokes throughout my brow. (self.com)
In other words, the open - jaw has to be the shortest side of the triangle. (travelcodex.com)
Fold the left and right sides of the triangle in to the middle line as shown in the photo to the left. (thespruce.com)