Laguerre cosine approximation<*** End of File ***>
Math history fun fact
I came across this some 50 years ago,
before calculators had trig keys.It's good to about 4 significant digits for first quadrant,
and exact at 0, 45, 60, 90 degrees.m = angle/90 for degrees or angle/pi/2 for radians
m^2
(   1)
sqrt((m^3 + 4m^2 5m + 2)/3) + mThis can be expressed in linear form as:
(((((((4m)m5)m+2)/3)^(1/2)+m)^(1)mm)1)
which can be keyed in directly on a simple chainlogic memory
calculator with a square root key and the ability to find the
reciprocal using some combination of / and = keys. Handle the
leading minus at the end, just mentally if necessary.To test it, on a 12C, for angles in degrees:
90 / ENTER ENTER ENTER
4 x<>y  X 5  X 2 + 3 / gsqrt + 1/x X X 1  CHS
OT: Cosine curio


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