Askor explained: I assumed trigonometric substitution only perform if there is on the market a square root like ##sqrt x^2 + 2 ##. No. Trig substitution is useful When you have the sum or big difference of squared conditions - they needn't be within a square root. Photon 'time bins' https://gabletoppak.com/how-i-integrated-branding-and-design-with-an-indian-paper-bottle-manufacturer/