Jawabanmu

2014-05-20T16:39:40+07:00
* Kll = PQ + QR + RS + PS = 18 cm + 13 cm + 8 cm + 13 cm = 52 cm
* mis t = TR
  TQ = (18 cm - 8 cm )/2 = 5 cm
  t = TR = √(13²-5²) = √144 = 12 cm
  L = jml ssj × (t / 2)
     = (18 + 8) × (12 / 2)
     = 26 × 6
     = 156 cm²