after 1 terms, the difference between cos(x) and aprox func is 2.9298012682724606
after 2 terms, the difference between cos(x) and aprox func is 1.1206867383942072
after 3 terms, the difference between cos(x) and aprox func is 0.2105196466234821
after 4 terms, the difference between cos(x) and aprox func is 0.023858254692953773
after 5 terms, the difference between cos(x) and aprox func is 0.0018181048161521884
after 6 terms, the difference between cos(x) and aprox func is 9.976362487795765e-05
after 7 terms, the difference between cos(x) and aprox func is 4.134263480115585e-06
after 8 terms, the difference between cos(x) and aprox func is 1.3403493681618528e-07
after 9 terms, the difference between cos(x) and aprox func is 3.493543787591591e-09
after 10 terms, the difference between cos(x) and aprox func is 7.481359975969326e-11
after 11 terms, the difference between cos(x) and aprox func is 1.3391510123028638e-12
after 12 terms, the difference between cos(x) and aprox func is 2.1094237467877974e-14
after 13 terms, the difference between cos(x) and aprox func is 4.440892098500626e-16
after 14 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16
after 15 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16
after 16 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16
after 17 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16
after 18 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16
after 19 terms, the difference between cos(x) and aprox func is 6.661338147750939e-16