Jawabanmu

2014-04-27T14:04:59+07:00
Luas belah ketupat = 1/2(diagonal 1 x diagonal 2)
4p^2+20=1/2(4p-4)(2p+4)
8p^2+40=8p^2+16p-8p-16
40+16=8p
56=8p
56/8=p
p=7
diagonal 1= 4(7)-4=24
diagonal 2 = 2(7)+4=18

mencari rusuk belah ketupat
r^2=(24/2)^2 + (18/2)^2
r^2=12^2+9^2
r^2=144+81
r^2=225
r=akar 225=15
keliling=4 x r=4x 15 = 60 cm