√2cosx=tanx=sinx/cosx√2(cosx)^2=√2-√2(sinx)^2=sinx√2(sinx)^2+sinx-√2=0√2[(sinx)^2+√2/2sinx +(√2/4)^2]-√2-√2/8=0√2(sinx+√2/4)^2=9√2/8(sinx+√2/4)^2=9/8=18/16=(±3√2/4)^2sinx+√2/4=±3√2...