第1个回答 2017-11-27
arctanx)'=1/(1+x^2)=1-x^2+x^4-...
arctanx = x - x^3/3 +x^5/5 - x^7/7 +....
π/4=arctan1=1-1/3+1/5-1/7+...
(arcsinx)' =1/√(1-x^2)=1+1/2x^2+(-1/2)(-3/2)/2*x^4+...,
arcsinx=x+1/6x^3+3/20 x^5+....
sinx=x-x^3/3!+x^5/5!...
cosx=1-x^2/2!+x^4/4!....
tanx=x+x^3/3+(2x^5)/15+(17x^7)/315+(62x^9)/2835