2cos(x+п/4)cos(2x+п/4)+sin3x -упростить

Question

2cos(x+п/4)cos(2x+п/4)+sin3x -упростить

Answer 1

2cos(x+п/4)cos(2x+п/4)+sin3x=2*1/2(cos(х+п/4-2х-п/4)+cos(х+п/4+2х+п/4)+sin3х=cosх+cos(3х+п/2)+sin3х=cosх-sin3х+sin3х=cosх