Вычислите: a)sin75 и cos75,заменяя 75 на 45+30 б)sin15 и cos15,заменяя 15 на 45-30

1) sin 75 = sin(45+30) = sin45*cos30 + cos45*sin30 = √2/2 * √3/2 + √2/2 * 1/2 = √2/4*(√3+1) cos 75 = cos(45+30) = cos45*cos30 - sin45*sin30 = √2/2 * √3/2 - √2/2 * 1/2 = √2/4*(√3+1) 2) sin 15 = sin(45-30) = sin45*cos30 + cos45*sin30 = √2/2 * √3/2 - √2/2 * 1/2 = √2/4*(√3+1) cos15 = cos(45+30) = cos45*cos30 - sin45*sin30 = √2/2 * √3/2 + √2/2 * 1/2 = √2/4*(√3+1)