Let secx + tanx = uY = ln (secx+tanx) = ln udy/dx = d(ln u)/dx = (1/u)*du/dx=(1/(secx + tanx)) * d(secx+tanx)/dx=(1/(secx + tanx)) * [(dsecx + dtanx)/dx]=(1/(secx + tanx)) * (secx*tanx + sec^2(x))= se...