Tolong dijawab ya soalnya mau dikumpulin :) ;)

Dik :
l = CD = 16 cm
r1 = AD = 15 cm
p = AB = 20 cm

Dit : r2?

Jawab :
[tex] {l}^{2} = {p}^{2} - {(r1 - r2)}^{2} \\ {16}^{2} = {20}^{2} - {(15 - r2)}^{2} \\ 256 = 400 - {(15 - r2)}^{2} \\ {(15 - r2)}^{2} = 400 - 256 \\ {(15 - r2)}^{2} = 144 \\ 15 - r2 = \sqrt{144} \\ 15 - r2 = 12 \\ r2 = 3[/tex]