2cos²(45°+4a)+sin8a=1

2cos²(45+4a) + sin8a = 1cos²x = (1+cos2x)/2   - формула2cos²(45+4a) +sin8a = 12(1+cos2(45+4a))/2 +sin8a = 11+cos2(45+4a) + sin8a   = 11+ cos(90+8a)+ sin8a = 1cos(90+a) = -sina   формула1+ cos(90+8a) + sin8a = 11-sin8a +sin8a  = 11 = 1