Jawabanmu

2014-04-12T18:17:20+07:00
S1 = x+4,
S2 = 3x+2, t = 2x dan L = 180
L = ½ (S1 + S2) t
180 = ½((x+4)+(3x+2))2x
180 = x(4x+6)
180 = 4x²+6x
0 = 4x²+6x-180 0 = 2(x-6)(2x+15)
x = 6 → memenuhi
x = -15/2 → tidak memenuhi
substitusi x = 6
S1 = 6+4 = 10 m
S2 = 3(6)+2 = 20 m
t = 2(6) = 12 m
s² = (½(S2-S1))² + t²
= (½(20-10))² + 12²
= 25 + 144 = 169 
s = √169 = 13 m
K = S1 + S2 + 2s = 10 + 20 + 2(13)
=  56 m

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