tanx=sinx/cosx=2 .sinx=2cosx.由sinx^2+cosx^2=1.4cosx^2+cosx^2=1.cosx=（5^0.5)/5或-（5^0.5)/52sinx+cosx/sinx+6(cosx)=4cosx+1/2+6(cosx)=1/2+2（5^0.5)或1/2-2（5^0.5)sinxcosx=2cosx^2=2/5