Askor reported: I believed trigonometric substitution only do the job if there is on the market a square root including ##sqrt x^two + two ##. No. Trig substitution is helpful For those who have the sum or distinction of squared terms - they don't need to be within a square https://gabletoppak.com/sustainable-liquid-soap-packaging-why-gabletop-cartons-are-the-eco-friendly-choice/