Дано
$$sin{left (x – 2 y right )} sin{left (5 x – 2 y right )} + cos{left (x – 2 y right )} cos{left (5 x – 2 y right )}$$
Подстановка условия
$$sin{left (x – 2 y right )} sin{left (5 x – 2 y right )} + cos{left (x – 2 y right )} cos{left (5 x – 2 y right )}$$
cos(5*x – 2*(-3/2))*cos(x – 2*(-3/2)) + sin(5*x – 2*(-3/2))*sin(x – 2*(-3/2))
$$sin{left (- 2 (-3/2) + x right )} sin{left (- 2 (-3/2) + 5 x right )} + cos{left (- 2 (-3/2) + x right )} cos{left (- 2 (-3/2) + 5 x right )}$$
cos(5*x – 2*(-3)/2)*cos(x – 2*(-3)/2) + sin(5*x – 2*(-3)/2)*sin(x – 2*(-3)/2)
$$sin{left (x – -3 right )} sin{left (5 x – -3 right )} + cos{left (x – -3 right )} cos{left (5 x – -3 right )}$$
cos(3 + x)*cos(3 + 5*x) + sin(3 + x)*sin(3 + 5*x)
$$sin{left (x + 3 right )} sin{left (5 x + 3 right )} + cos{left (x + 3 right )} cos{left (5 x + 3 right )}$$
Численный ответ
cos(x – 2*y)*cos(5*x – 2*y) + sin(x – 2*y)*sin(5*x – 2*y)
Общее упрощение
/ 2
| 2 / 2 4 |
5 – 8*sin (y) – 4*1 – sin (y)/ + 4*sin (y)/*cos(4*x)
$$left(- 4 left(- sin^{2}{left (y right )} + 1right)^{2} + 4 sin^{4}{left (y right )} – 8 sin^{2}{left (y right )} + 5right) cos{left (4 x right )}$$
Соберем выражение
$$cos{left (4 x right )}$$
Тригонометрическая часть
/ 2
| 2 / 2 4 |
5 – 8*sin (y) – 4*1 – sin (y)/ + 4*sin (y)/*cos(4*x)
$$left(- 4 left(- sin^{2}{left (y right )} + 1right)^{2} + 4 sin^{4}{left (y right )} – 8 sin^{2}{left (y right )} + 5right) cos{left (4 x right )}$$
Раскрыть выражение
(cos(x)*cos(2*y) + sin(x)*sin(2*y))*(cos(2*y)*cos(5*x) + sin(2*y)*sin(5*x)) + (cos(x)*sin(2*y) – cos(2*y)*sin(x))*(cos(5*x)*sin(2*y) – cos(2*y)*sin(5*x))
$$left(sin{left (x right )} sin{left (2 y right )} + cos{left (x right )} cos{left (2 y right )}right) left(sin{left (5 x right )} sin{left (2 y right )} + cos{left (5 x right )} cos{left (2 y right )}right) + left(- sin{left (x right )} cos{left (2 y right )} + sin{left (2 y right )} cos{left (x right )}right) left(- sin{left (5 x right )} cos{left (2 y right )} + sin{left (2 y right )} cos{left (5 x right )}right)$$