cos2x+sin2x
=√2(√2/2*cos2x+√2/2*sin2x)
=√2cos(2x-π/4)
cos2x-sin2x
=√2(√2/2*cos2x-√2/2*sin2x)
=√2cos(2x+π/4)
cos2x+sin2x
=√2(√2/2cos2x+√2/2sin2x)
=√2sin(2x+π/4)
cos2x-sin2x
=√2(√2/2cos2x-√2/2sin2x)
=√2sin(π/4-2x)
cos2x+sin2x=√2sin(2x+π/4)
cos2x-sin2x=√2cos(2x+π/4)
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