I1=∫(sinx)^6 dx=-∫(sinx)^5 dcosx = -cosx (sinx)^5 + ∫cosxd(sinx)^5 =-cosx (sinx)^5 + 5∫cosx(sinx)^4 cosxdx =-cosx (sinx)^5 + 5∫(sinx)^4 - (sinx)^6dx6I1 =-cosx (sinx)^5 + 5∫(sinx)^4dx ----1I2 = ...