13-5=8
13-8=5
8+5=13
<span>5+8=13</span>
Ответ:
Пошаговое объяснение: число кратное4 --20%
число больше 11 --0% так как карточек 10 и нумерация их от 1 до 10
2cos x + 2 - 2sin x cos x - 2sin x = 0
2 cos x + 1 + sin²x - 2sin x cos x + cos²x - 2sin x = 0
2(cos x - sin x) + (cos x - sin x)² + 1 = 0
Пусть cos x - sin x = t, тогда
t² + 2t + 1 =0
(t + 1)² = 0
t = -1
sin x - cos x = 1
![2sin \frac{x}{2} cos \frac{x}{2} -cos^2\frac{x}{2} +sin^2 \frac{x}{2} =sin^2\frac{x}{2} +cos^2\frac{x}{2}](https://tex.z-dn.net/?f=2sin+%5Cfrac%7Bx%7D%7B2%7D+cos+%5Cfrac%7Bx%7D%7B2%7D+-cos%5E2%5Cfrac%7Bx%7D%7B2%7D+%2Bsin%5E2+%5Cfrac%7Bx%7D%7B2%7D+%3Dsin%5E2%5Cfrac%7Bx%7D%7B2%7D+%2Bcos%5E2%5Cfrac%7Bx%7D%7B2%7D)
![2sin \frac{x}{2} cos \frac{x}{2} -cos^2\frac{x}{2} -2cos^2\frac{x}{2} =0](https://tex.z-dn.net/?f=2sin+%5Cfrac%7Bx%7D%7B2%7D+cos+%5Cfrac%7Bx%7D%7B2%7D+-cos%5E2%5Cfrac%7Bx%7D%7B2%7D+-2cos%5E2%5Cfrac%7Bx%7D%7B2%7D+%3D0)
![cos \frac{x}{2} (sin \frac{x}{2} -cos \frac{x}{2} )=0](https://tex.z-dn.net/?f=cos+%5Cfrac%7Bx%7D%7B2%7D+%28sin+%5Cfrac%7Bx%7D%7B2%7D+-cos+%5Cfrac%7Bx%7D%7B2%7D+%29%3D0)
![cos \frac{x}{2} =0](https://tex.z-dn.net/?f=cos+%5Cfrac%7Bx%7D%7B2%7D+%3D0)
или
![sin \frac{x}{2} -cos \frac{x}{2} =0](https://tex.z-dn.net/?f=sin+%5Cfrac%7Bx%7D%7B2%7D+-cos+%5Cfrac%7Bx%7D%7B2%7D+%3D0)
![\frac{x}{2} = \frac{ \pi }{2} + \pi k](https://tex.z-dn.net/?f=+%5Cfrac%7Bx%7D%7B2%7D+%3D+%5Cfrac%7B+%5Cpi+%7D%7B2%7D+%2B+%5Cpi+k)
или
![tg \frac{x}{2} =1](https://tex.z-dn.net/?f=tg+%5Cfrac%7Bx%7D%7B2%7D+%3D1)
![x= \pi +2 \pi k](https://tex.z-dn.net/?f=x%3D+%5Cpi+%2B2+%5Cpi+k)
или
![x= \frac{ \pi }{2} +2 \pi n](https://tex.z-dn.net/?f=x%3D+%5Cfrac%7B+%5Cpi+%7D%7B2%7D+%2B2+%5Cpi+n)
Ответ:
![\pi +2 \pi k;\frac{ \pi }{2} +2 \pi n,\ k,n \in Z](https://tex.z-dn.net/?f=+%5Cpi++%2B2+%5Cpi+k%3B%5Cfrac%7B+%5Cpi+%7D%7B2%7D+%2B2+%5Cpi+n%2C%5C+k%2Cn+%5Cin+Z)