Тригонометрия Задание 23

Решите задачу:

$\frac{10}{ \sqrt{2} } \times ctg135 \times sin210 \times cos225 = \frac{10}{ \sqrt{2} } \times ctg(180 - 45) \times sin(180 + 30) \times cos(180 + 45) = \frac{10}{ \sqrt{2} } \times ( - ctg45) \times ( - sin30) \times ( - cos45) = \frac{10}{ \sqrt{2} } \times ( - 1) \times ( - \frac{1}{2} ) \times ( - \frac{ \sqrt{2} }{2} ) = - \frac{5}{2}$