2)When wil lyou decorate your Christmas tree?-On Christmas Eve.We bought new colourful balls yesterday
3)Do you like sports?-Yes,I like running and riding my bike.
4)In December <span>people </span> come home to their friends to cougratulate with New Year and Christmas
Известны две формулы площади сектора (Р-длина дуги, r - радиус)
![S= \frac{1}{2}*P*r \\ S= \frac{ \pi *r^{2}* \alpha }{360}](https://tex.z-dn.net/?f=S%3D+%5Cfrac%7B1%7D%7B2%7D%2AP%2Ar+%5C%5C+S%3D+%5Cfrac%7B+%5Cpi+%2Ar%5E%7B2%7D%2A+%5Calpha++%7D%7B360%7D+)
Приравняем их:
![\frac{1}{2}*2*r= \frac{ \pi *r ^{2}*60 }{360} \\ r= \frac{3.14*r ^{2} }{60} \\ 60r=3.14*r^{2} \\ r(3.14*r-6)=0 \\ r _{1} =0 \\ r _{2}=6/3.14=1.91](https://tex.z-dn.net/?f=+%5Cfrac%7B1%7D%7B2%7D%2A2%2Ar%3D+%5Cfrac%7B+%5Cpi+%2Ar+%5E%7B2%7D%2A60+%7D%7B360%7D+++%5C%5C+r%3D+%5Cfrac%7B3.14%2Ar+%5E%7B2%7D+%7D%7B60%7D++%5C%5C+60r%3D3.14%2Ar%5E%7B2%7D++%5C%5C+r%283.14%2Ar-6%29%3D0+%5C%5C+r+_%7B1%7D+%3D0+%5C%5C+r+_%7B2%7D%3D6%2F3.14%3D1.91++)
r=1.91см
![S= \frac{1}{2} *2*1.91=1.91=1.9](https://tex.z-dn.net/?f=S%3D+%5Cfrac%7B1%7D%7B2%7D+%2A2%2A1.91%3D1.91%3D1.9)
S = 1.9 см²
ЕР=30 см
ЕN=ЕР-7=30-7=23 см
EF=EN-10=23-10=13 см
Ответ: EF=13 см