Use your angle wedges to measure angles by lining up the pointy part with the angle you want to measure.
You can use more than one angle wedge to measure an angle.
For a 180º angle, which is a straight line, you can use two 90º angle wedges. You will need to line up the center of one of the angle wedges with the angle you want to measure. Then line up the center of the second wedge with the remaining part of the angle.