1/(cosx)^3 = (secx)^3∫(secx)^3dx = ∫secxdtanx=secx.tanx - ∫secx.(tanx)^2dx=secx.tanx - ∫secx.[(secx)^2-1]dx2∫(secx)^3dy =secx.tanx + ∫secxdx=secx.tanx + ln|secx+tanx|∫(secx)^3dy = (1/2)[secx.ta...