We are goin to need a picture in order to explain it well. What you need to do is to take the whole alphabet - I'd suggest using the same font, like in the example and writing the whole alphabet from A to Z.
You can print parts of it on A4 hard paper and then cut the letter out and paste them on a bigger sheet. After that, using a well distinguishable colour add lines showing how the angles look like in those letters.
Mark Acute, Obtuse and Right angles with different colour each so they would be clearly visible to anyone takes a peak at your project.
Please use the picture as a refference :)