Askor stated: I assumed trigonometric substitution only perform if there is available a square root such as ##sqrt x^2 + two ##. No. Trig substitution is helpful if you have the sum or variance of squared terms - they need not be inside of a square root. This is supported https://gabletoppak.com/free-water-advertising-a-sustainable-and-emotional-path-to-powerful-brand-recognition/