(1)3x=+/-(π/2-x)+2kπ,故x=+/- π/4+kπ(k∈Z)
(2)sin^2x+cos^2x=1=2sinxcosx+sinx-cosx
即(sinx-cosx)^2=sinx-cosx
则sinx-cosx=0或1,若sinx-cosx=0则x=+/-(π/2-x)+2kπ,x=π/4+kπ(k∈Z),
若sinx-cosx=1,即√2sin(x-π/4)=1 ,则x-π/4=π/4+kπ,x=π/2+kπ(k∈Z)
故x=π/4+kπ或π/2+kπ(k∈Z)
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