Askor stated: I assumed trigonometric substitution only work if there is obtainable a square root such as ##sqrt x^2 + two ##. No. Trig substitution is useful For those who have the sum or change of squared terms - they needn't be inside of a sq. root. Simple to use, https://gabletoppak.com/how-gabletop-cartons-are-helping-water-brands-combat-climate-change/