若tan(a+兀/4)=2,则1-cos2a/sin2a等于多少

问题描述:

若tan(a+兀/4)=2,则1-cos2a/sin2a等于多少

你是问(1-cos2a)/sin2a吧?还是1-(cos2a/sin2a)?tan(A+B) = (tanA+tanB)/(1-tanAtanB)tan(a+兀/4)= (tana+tan兀/4)/(1-tana *tan兀/4)= (tana+1)/(1-tana)=2所以tana=1/3cos2a=2(cosa)^2-1(1-cos2a)/sin...