Jawabanmu

2014-05-08T14:50:30+07:00
Phytagoras 20 - 12 = 16
qp = 16

12.16 = 192

192 = 20 . QR . 1/2
192 = 10. QR
19,2 = QR 
2014-05-08T14:52:02+07:00
PQ =√20²-12²
      =√400- 144
      =√256
      =16 cm

Luas segitiga = (PQ x OQ) : 2 = (16 x 12) : 2 = 96 cm²
Luas layang layang = 2 xluas segitiga
= 96 x 2 = 192 cm²

Luas layang-layang = 1/2 x OP x QR
192 = 1/2.20.QR
192=10 x QR
QR = 192 :10 =19,2 (c)