mohon bantuannya dengan cara terimakasih

s = ½ kell Δ = ½ (5+8+7) = 10
Luas Δ = √[s (s-a) (s-b) (s-c)] = √[10 (10-5)(10-8)(10-7)] = √[10.5.2.3] = 10√3 cm²
Jari" lingkaran dlm = Luas Δ/s = (10√3)/10 = √3 cm

s = ½ kel segitiga = 5 + 8 + 7 = 20/2 = 10
r =√ s (s-a) (s-b) (s-c)/s
r = √ 10 (10-5) (10-8) (10-7) / 10
= √ 10.5.2.3 /10
= √300/10 = √30