∫sint/(cost+sint)dt= (1/2)∫[(sint+cost) +(sint-cost) ]/(cost+sint)dt=(1/2)∫ dt + (1/2)∫(sint-cost)/(cost+sint)dt=(1/2)∫ dt - (1/2)∫dln(sint+cost)=(1/2)t - (1/2)ln|sint+cost| + C