Воспользуемся формулой понижения степеней
![\cos^2 \alpha = \frac{1+\cos2 \alpha }{2}](https://tex.z-dn.net/?f=%5Ccos%5E2+%5Calpha+%3D+%5Cfrac%7B1%2B%5Ccos2+%5Calpha+%7D%7B2%7D+)
![10 \sqrt{2} \cdot \cos^2 \frac{15 \pi }{8} -5\sqrt{2} =10\sqrt{2} \cdot \dfrac{1+\cos \frac{15 \pi }{4} }{2} -5\sqrt{2} =\\ \\ \\ =5\sqrt{2} (1+\cos(4 \pi - \frac{\pi}{4} ))-5\sqrt{2} =5\sqrt{2} (1+\cos \frac{\pi}{4})-5\sqrt{2} =\\ \\ \\ =5\sqrt{2} (1+ \frac{1}{ \sqrt{2} } )-5\sqrt{2} =5\sqrt{2} +5-5\sqrt{2} =5](https://tex.z-dn.net/?f=10+%5Csqrt%7B2%7D+%5Ccdot+%5Ccos%5E2+%5Cfrac%7B15+%5Cpi+%7D%7B8%7D+-5%5Csqrt%7B2%7D+%3D10%5Csqrt%7B2%7D+%5Ccdot+%5Cdfrac%7B1%2B%5Ccos+%5Cfrac%7B15+%5Cpi+%7D%7B4%7D+%7D%7B2%7D+-5%5Csqrt%7B2%7D+%3D%5C%5C+%5C%5C+%5C%5C+%3D5%5Csqrt%7B2%7D+%281%2B%5Ccos%284+%5Cpi+-+%5Cfrac%7B%5Cpi%7D%7B4%7D+%29%29-5%5Csqrt%7B2%7D+%3D5%5Csqrt%7B2%7D+%281%2B%5Ccos+%5Cfrac%7B%5Cpi%7D%7B4%7D%29-5%5Csqrt%7B2%7D+%3D%5C%5C+%5C%5C+%5C%5C+%3D5%5Csqrt%7B2%7D+%281%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D+%29-5%5Csqrt%7B2%7D+%3D5%5Csqrt%7B2%7D+%2B5-5%5Csqrt%7B2%7D+%3D5)
5\8+3\8=1
1\5+4\5=1
7\8+1\8=1
2\5+3\5=1
1,4\7+3\7=2
8\7+6\6=2
1,3\4+1\4=2
5\4+3\4=2
2,1\2+1\2=3
1,1\2+3\2=3
1,5\6+1,1\6=3
1,4\6+8\6=3
Всего было 9/9 стр.
9/9-5/9=4/9 - осталось на 2 день
4/9 - это 16 страниц
16:4*9=36 страниц в рукописи.
А)<span>(х+27)-12=42
</span><span>х+27-12=42
</span>х=27
<span>б) 115-(35+у)=39
</span><span>115-35+у=39
</span>у=-41
<span>в) z-35-64=16
</span>z=115
<span>г) 28-t+35=53
-t=-10
t=10</span>
314 х 75 = 23550 - верно
601 х 852 = 512052 - верно