The smallest angle of a 3-4-5 triangle is 36.87 degrees = atan(3/4). One way to get a decent approximation is as atan(1) - atan(1/7). The first term is 45 degrees, and the second is fairly approximated as 1/7 radians, which is 57.3/7 = ~ 8.2 degrees. This gives 36.8 degrees as an approximate answer. The first neglected term in the atan power series is 1/3*7^3 = 1/1029, so the approximation is decent. The nearness to 36 degrees makes the 3-4-5 triangle helpful in drawing approximate regular pentagons on graph paper. Rich rcs@cs.arizona.edu PS: Let's try to avoid political discussions. We've all been through the arguments about the quality of math education and related topics. Unless you have something truly new to say on the subject, there's no benefit to reiteration on this mailing list.