30分求助,请问根号1+sina-根号1-sina,a属于(0,180度)如何化简?RT,越快越好啊

原式=根号(sina/2^2+2sina/2*cosa/2+cosa/2^2)-根号(sina/2^2-2sina/2*cosa/2+cosa/2^2)
=sina/2+cosa/2-sina/2+cosa/2
=2cosa/2

因为1+sina=[sin(a/2)+cos(a/2)]^21-sina==[sin(a/2)-cos(a/2)]^2故原式=|sin(a/2)+cos(a/2)]|-|sin(a/2)-cos(a/2)|因为a属于(0,180度),a/2属于(0,90)当a属于(0,90度]时,a/2属于(0,45度],0