Mohon bantuan nya gengs Tolong di jawab! Ya!!

s = 1/2 (20+34+42)
=1/2 (96)
=48
L.segitiga= √s(s-pq) (s-ar) (s-pr)=
= √48(48-20)(48-34)(48-42)
= √48.28.14.6
= √112896
= 336cm2
r = PQ . QR . PR / 4 .L segitiga
= 20 . 34 . 42 / 4 . 336
= 4 . 34 . 42 / 336
= 7140 / 336
= 21,25 cm