diketahui tarapesium ABCD. CD=8cm BC=12cm dan tinggi= 10cm maka luas trapesium tersebut... a.180cm b.170cm c.160cm d.150cm Mohon dengan cara nya

L=(a+b)×t/2
  =(8cm+(8cm+2(√(12cm)²-(10cm²))×10cm/2
  =(8cm+(8cm+2(√144cm²-100cm²))×5cm
  =(8cm+(8cm+2(√44cm²))×5cm
  =(8cm+(8cm+2(2√11cm))×5cm
  =(8cm+(8cm+4√11cm))×5cm
  =(16cm+4√11cm)×5cm
  =80cm²+20√11cm²