# Math Help - inverse trig and geometric series

1. ## inverse trig and geometric series

I learned about series recently. I noticed a slight similarity between a geometric series $\sum_{n=0}^{\infty} ar^{n} = \frac{a}{1-r}; |r| < 1$

and a integral, say $\int_{a}^{b} \frac{1}{1-x^2}dx$

can you solve using a series instead of trig sub?

2. ## Re: inverse trig and geometric series

u can use the fact that 1/(1-x)=1+x+x^2+x^3+..
so 1/(1-x^2)=1+x^2+x^4+...
now if u have read truncation rule
u can take first three terms only and rest can be assigned as O(x^n)
this would give u the approximated result