答：(0→x) ∫ (sint+costsint) dt=(0→x) -∫ (1+cost) d(cost)=(0→x) -cost-(1/2)(cost)²=-cosx-(1/2)(cosx)²-(-1-1/2)=-(1/2)(cosx)²-cosx+3/2=-(1/2)(cosx+1)²+2当且仅当cosx=-1时,原式最...