Askor claimed: I thought trigonometric substitution only function if there is out there a sq. root for example ##sqrt x^2 + two ##. No. Trig substitution is useful For those who have the sum or difference of squared terms - they needn't be inside a square root. Ad It is https://gabletoppak.com/hc-issues-notice-over-plea-to-make-dwarka-plastic-free/