а) cos(z+y) - sin(z)cos(y) = coszcosy - sinzcosy - sinzcosy = coszcosy - 2sinz*cosy = cos(z+y) - sin(z+y) = sin(z+y)
б) sin(x-π/4) + √2/2*cos(x) = sinxcos(π/4) - cosxsin(π/4) + √2/2cosx = sinx(√2/2) - cosx(√2/2) + √2/2cosx = (√2/2)sinx - (√2/2)cosx + √2/2cosx = √2/2sinx
а) cos(z+y) - sin(z)cos(y) = coszcosy - sinzcosy - sinzcosy = coszcosy - 2sinz*cosy = cos(z+y) - sin(z+y) = sin(z+y)
б) sin(x-π/4) + √2/2*cos(x) = sinxcos(π/4) - cosxsin(π/4) + √2/2cosx = sinx(√2/2) - cosx(√2/2) + √2/2cosx = (√2/2)sinx - (√2/2)cosx + √2/2cosx = √2/2sinx