Tolong bantuin dong, pls banget

k = 1/2 (4 + 6 + 8)
k = 9

radius (r)
= akar (k (k - 4)(k - 6)(k - 8)) / k
= akar (9 . 5 . 3 . 1) / 9
= akar 135 / 9
= 1/3 akar 15

Jawab B

s= 1/2(a+b+c)
  = 1/2(4+6+8)
  = 9 cm

r = √s(s-a)(s-b)(s-c)/s
  = √9(9-4)(9-6)(9-8)/9
  =√9 x 5 x 3 x 1/9
  =√135 / 9
  =b. 1/3√15 cm²