Askor said: I assumed trigonometric substitution only perform if there is on the market a square root for instance ##sqrt x^2 + 2 ##. No. Trig substitution is helpful Should you have the sum or change of squared terms - they needn't be inside a sq. root. , or flat. https://gabletoppak.com/india-leads-in-generating-plastic-waste-with-10-2-mn-tonnes-a-year-study/