∵sin(π-x)+cos(π+x)=1/5==>sinx-cosx=1/5.(1)==>(sinx-cosx)²=1/25==>2sinxcosx=24/25∴(sinx+cosx)²=sin²x+2sinxcosx+cos²x=1+2sinxcosx=1+24/25=49/25∴sinx+cosx=±7/5.(2)∵0