Place the protractor flat on a piece of paper. Hold the protractor in place with one hand so that the curved side is furthest from you. Draw a center point where you want the crown of the arch to be.
Determine the size arch you want to make by looking at the angle degrees. Move the protractor so that the arch will be upright and centered with the same number of degrees on each side of the crown's center point.
Trace the top curved part of the protractor from one end to the chosen degree.
Draw the piers of the arch. Line the straight edge of the protractor up to the left end point of the arch curve. Draw a straight line that extends from the side of the arch. Repeat the process on the right side.
Decide how wide you want the piers of the arch to be. Line a ruler up to the bottom of the drawn line to measure an equal length for the bottom of both piers. Draw a straight line to make the pier bottoms.
Measure a length with your ruler for the interior lines of the piers. Connect the lines to the bottom of the piers inside the arch. Leave space to connect the interior lines to each other with a smaller interior arch.
Place the curved side of your protractor between the interior pier lines to create a similar, yet resized version of the exterior curve. Trace the curved side of the protractor to connect the interior curve to the interior pier lines to complete your arch.