Jawabanmu

2014-03-01T21:36:09+07:00
S = 1/2 (26+28+38)
  = 46 cm
L = 1/2 x a x t
   = 1/2 x 26 x 28
   = 364 cm²
a) r = L/s
      = 364/46
      = 7,9 cm
b) r = abc/4L
     = 26 x 28 x 38 / 4 x 364
     = 27.664/1456
     = 19 cm
6 4 6