Jawabanmu

2013-12-30T07:32:54+07:00
Panjang busur 
2,5= \frac{ \alpha^0 }{360^0}\times keliling\\ 
2,5= \frac{ \alpha^0 }{360^0}\times 2\pi r\\

luas juring
5= \frac{ \alpha ^0}{360^0}\times luas\\ 
5= \frac{ \alpha ^0}{360^0}\times 6\pi\\ 
\frac{ \alpha ^0}{360^0}\times 6\pi=5\\ 
\frac{ \alpha ^0}{360^0}=\frac{5}{6\pi}\\ 


substitusikan ke pers 1
2,5= \frac{ \alpha^0 }{360^0}\times keliling\\
2,5= \frac{ 5 }{6 \pi }\times keliling\\
keliling = 2,5\times  \frac{6\pi}{5}\\
keliling = 3\pi