To help you visualize the Sails, you can also use string stretched between your planned attachment points. The first step is to measure. Then make a scale drawing of the area you want shaded. 1/4 (or 1/8) inch = 1 foot. Then cut out scale drawings of the ready-made shade sails. Rotate them around to get ideas for the lay-out. Imagine a straight line from the center of the shade sail through the corner ring, that is where you need to put the attachment point.
Angle Bisectors in a Triangle. The definition of the angle bisector of a triangle is a line segment that bisects one of the vertex angles of a triangle. In general, an angle bisector is equidistant from the sides of the angle when measured along a segment perpendicular to the sides of the angle. Click on image for interactive Geometer's Sketchpad version.
Here the blue line segment is bisected by the red line: You can try it yourself (try moving the points): View Larger. When the bisector is perpendicular to the line being bisected it is called a perpendicular bisector.