2cos²(45+4a) + sin8a = 1 cos²x = (1+cos2x)/2 - формула 2cos²(45+4a) +sin8a = 1 2(1+cos2(45+4a))/2 +sin8a = 1 1+cos2(45+4a) + sin8a = 1 1+ cos(90+8a)+ sin8a = 1 cos(90+a) = -sina формула 1+ cos(90+8a) + sin8a = 1 1-sin8a +sin8a = 1 1 = 1