Jawabanmu

2014-01-28T19:33:57+07:00
A. a+3a= 28
4a=28
a=28:4=7
b. 22/7 x7=22
22/7x3x7=66
jadi , 22/66 1/3 atau 1:3
c. keliling b -keliling a
= 66-22 =44

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2014-01-28T19:38:40+07:00
A.) a+3a=28
4a=28
a=7 ---->jari" ke 1
3a=21-----> jari" ke 2
b.) luas 1 : luas 2
= π× r^{2} : π× r^{2}
=  7^{2} :  21^{2}
= 49 : 441
= 1 : 9
keliling 1 : keliling 2
= π×d :π×d
= 14 : 42
=1:3
c..) luas 1=  \frac{22}{7} × 7^{2} = 154
luas 2=  \frac{22}{7} ×  21^{2} = 1386
selisih luas = 1386-154= 1232
keliling 1 =  \frac{22}{7} ×14= 44
keliling 2=  \frac{22}{7} ×42=132
selisih keliling= 132-44=88


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