Askor claimed: I believed trigonometric substitution only function if there is obtainable a sq. root for example ##sqrt x^two + 2 ##. No. Trig substitution is useful if you have the sum or variation of squared conditions - they don't need to be within a sq. root. Easy to use, https://gabletoppak.com/why-i-switched-to-water-in-a-sustainable-box/