Jawabanmu

2014-05-31T19:44:43+07:00
5 = √p² - (R+r)²
5 = √p² - 144
169 = p²
p = 13 cm
2014-05-31T19:46:05+07:00
  5 = √x² - (8+4)²
  5 = √x² - 12²
  5 = √x² -144
  25 = x² -144
 144+25 = x²
169 = x²
√169 = x
13 = x