Jawabanmu

2014-02-13T00:04:13+07:00
1. PQ/EP = AP/PR
2. EP = PQ x PR/AP = 2r
3. L ΔPQR = QR x AP/2
    AP = 2L/QR
    2r = PQ x PR/ 
 \frac{2L}{QR}
    2r = PQ x QR x PR/2L
      r = PQ x QR x PR /4L
      r = 40 x 42 x 58/4L
      r = 97440/24360
      r = 4