∫ 1/(1 - v²/a²) dv= a∫ a/(a² - v²) dv= (a/2)∫ [(a - v) + (a + v)]/(a² - v²) dv= (a/2)∫ [1/(a + v) + 1/(a - v)] dv= (a/2)[ln|a + v| - ln|a - v|] + C= (a/2)ln| (a + v)/(a - v) | + C
