When x tends to 0, SiNx arctanx is used to find the limit

When x tends to 0, SiNx arctanx is used to find the limit

First use Taylor formula to get: SiNx = x - x ^ 3 / 3! + x ^ 5 / 5! - x ^ 7 / 7! + x ^ 9 / 9 Arctan x = x - x ^ 3 / 3 + x ^ 5 / 5 - x ^ 7 / 7 - x ^ 9 / 9... So SiNx - arctan x = (x - x ^ 3 / 3! + x ^ 5 / 5! - x ^ 7 / 7! + x ^ 9 / 9!) ) - (x - x^3 / 3 + x^...