Carpenter's Square

References

Loomis, E. S. "The Carpenter's Square." §3.6 in The Pythagorean Proposition: Its Demonstrations Analyzed and Classified and Bibliography of Sources for Data of the Four Kinds of "Proofs," 2nd ed. Reston, VA: National Council of Teachers of Mathematics, pp. 29-30, 1968.Scudder, H. T. "How to Trisect and Angle with a Carpenter's Square." Amer. Math. Monthly 35, 250-251, 1928.