What is #int 1/ sqrt(x^2 - 8^2) dx#? Calculus Introduction to Integration Integrals of Trigonometric Functions 1 Answer F. Javier B. Apr 23, 2018 See below Explanation: Try the change #x=8sectheta# Then #dx=8secthetatanthetad theta# #int1/(sqrt(x^2-8))dx=int(sqrt8secthetatanthetad theta)/sqrt(8^2(sec^2theta-1))=# #=int(cancel8secthetacanceltanthetad theta)/(cancel8canceltantheta))=intsecthetad theta=ln(sectheta+tantheta)+C=ln(x/8+sqrt(x^2-8^2)/8)+C# Answer link Related questions How do I evaluate the indefinite integral #intsin^3(x)*cos^2(x)dx# ? How do I evaluate the indefinite integral #intsin^6(x)*cos^3(x)dx# ? How do I evaluate the indefinite integral #intcos^5(x)dx# ? How do I evaluate the indefinite integral #intsin^2(2t)dt# ? How do I evaluate the indefinite integral #int(1+cos(x))^2dx# ? How do I evaluate the indefinite integral #intsec^2(x)*tan(x)dx# ? How do I evaluate the indefinite integral #intcot^5(x)*sin^4(x)dx# ? How do I evaluate the indefinite integral #inttan^2(x)dx# ? How do I evaluate the indefinite integral #int(tan^2(x)+tan^4(x))^2dx# ? How do I evaluate the indefinite integral #intx*sin(x)*tan(x)dx# ? See all questions in Integrals of Trigonometric Functions Impact of this question 3917 views around the world You can reuse this answer Creative Commons License