My Table of Integrals has the overall situation ##int frac dx x^2+a^2 ## for a 'standard' integral way too, not just the situation where ##a=1##. But I think this remaining a Calculus homework dilemma it is expected on the OP to figure out how to get it done. Hints got https://gabletoppak.com/choosing-between-gable-top-packaging-and-plastic-bottles-for-your-beverage-business/