If f(x)=sinx-cosx is written as f1(x)+f2(x) where f1(x) is even and f2(x) is odd then
f1(x)=cosx
f1(x)=-cosx
f2(x)=-sinx+cosx
f2(x)=sin(2π-x)
f1(x)=f(x)+f(-x)2=12Sinx-cosx-sinx-cosx=-cosx f2(x)=f(x)-f(-x)2=12sinx-cosx+sinx+cosx=sinx