Question

Вычислите
1)Cos123cos57-sin123*sin57=
2)sin69cos21+cos69*sin21=
(Обязательно решение)

Answer 1

1)Cos123cos57-sin123*sin57= cos(123 + 57) = cos(180) = -1
2)sin69cos21+cos69*sin21= sin(69 + 21) = sin(90) = 1