Brodetsky, Selig, 1888-1954 · London, G. Bell and Sons, Ltd. · leaf 119
TRIGONOMETRICAL FUNCTIONS 101 We at once get, since sec-x=l +tan^a:^, the equation (e-«)^-(e-^)^=(/3-«)v, 2J = (/3-«),,2 4-(/3 + a). I.e. … To get the simplest result, we therefore use This gives 2^=2l3r,\ Hence we choose 13 = 1, a=— 1, and the x curve is the parabola J='r. The graduations are seen to be given by slna; = i+?
Nomography (Mathematics)
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