Jawabanmu

2014-04-02T23:56:28+07:00
Diameter = 7 m 
r = 7/2 m

luas permukaan 1/2 bola = 1/2 (4  \pi   r^{2} )
                                    = 1/2 (4 . 22/7 .  (7/2)^{2}
                                    = 77  m^{2}
biaya 30.000 x 77 = 2.310.000
2014-04-03T03:11:56+07:00
Rp 210000diameter 7 meter. Jika harga katun Rp 30,000 setiap m2