sin(p/4-a)sin(p/4+a) -cos(p/4+a)cos(p/4-a)
Помогите срочно ​

Ответ:

0

Объяснение:

sin(π/4 - a) · sin(π/4 + a) - cos(π/4 + a) · cos(π/4 - a) =

0.5 cos (π/4 - a - π/4 - a) - 0.5cos (π/4 - a + π/4 + a) -

- 0.5 cos (π/4 - a + π/4 + a) - 0.5 cos (π/4 + a - π/4 + a) =

= 0.5cos (-2a) - 0.5cos π/2 - 0.5cos π/2 - 0.5cos 2a =

= 0.5cos (2a) - 0.5cos π/2 - 0.5cos π/2 - 0.5cos 2a

= -cos π/2 = 0