Фотография->смотри. Нужно 20 символов.
cosx cos2x cos4x cos8x cos16x cos32x =
= (2sinxcosx / 2sinx) cos2x cos4x cos8x cos16x cos32x =
= (sin2x / 2sinx) cos2x cos4x cos8x cos16x cos32x =
= (sin2x / 2sinx) (2sin2xcos2x / 2sin2x) cos4x cos8x cos16x cos32x =
= (sin4x / 4sinx) (2sin4xcos4x / 2sin4x) cos8x cos16x cos32x =
= (sin8x / 8sinx) (2sin8xcos8x / 2sin8x) cos16x cos32x =
= (sin16x / 16sinx) (2sin16xcos16x / 2sin16x) cos32x =
= (sin32x / 32sinx) (2sin32xcos32x / 2sin32x) =
= sin64x / 64sinx
x = π/9
![\frac{sin\frac{64\pi}{9}}{64sin\frac{\pi}{9}}=\frac{sin(7\pi+\frac{\pi}{9})}{64sin\frac{\pi}{9}}= \frac{sin7\pi cos\frac{\pi}{9}+cos7\pi sin\frac{\pi}{9}}{64sin\frac{\pi}{9}} = \frac{-sin\frac{\pi}{9}}{64sin\frac{\pi}{9}} = -\frac{1}{64}](https://tex.z-dn.net/?f=%5Cfrac%7Bsin%5Cfrac%7B64%5Cpi%7D%7B9%7D%7D%7B64sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%3D%5Cfrac%7Bsin%287%5Cpi%2B%5Cfrac%7B%5Cpi%7D%7B9%7D%29%7D%7B64sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%3D%20%5Cfrac%7Bsin7%5Cpi%20cos%5Cfrac%7B%5Cpi%7D%7B9%7D%2Bcos7%5Cpi%20sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%7B64sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%20%3D%20%5Cfrac%7B-sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%7B64sin%5Cfrac%7B%5Cpi%7D%7B9%7D%7D%20%3D%20-%5Cfrac%7B1%7D%7B64%7D)
Поменяем знак во втором неравенстве:
![0{,}8<3{,}3](https://tex.z-dn.net/?f=0%7B%2C%7D8%3C3%7B%2C%7D3)
Теперь сложим почленно:
![0{,}8+16<3{,}3+23\\16{,}8<26{,}3](https://tex.z-dn.net/?f=0%7B%2C%7D8%2B16%3C3%7B%2C%7D3%2B23%5C%5C16%7B%2C%7D8%3C26%7B%2C%7D3)