Question

Suatu segitiga ABC siku siku di A. jika panjang AB = 18 cm, AC = 24 cm, maka jari jari lingkaran dalamnya adalah ? ° >
° >

Answer 1

Pnjng BC = √18²+24²
=√324+576
=√900 = 30cm

jri²ling dlam = L△ / ½K△
=(18×24/2)/(18+24+30/2)
=216/72
= 3 cm

Answer 2

(BC)² = 18² + 24²
(BC)² = 324 + 576
(BC)² = 900
BC = √900 = 30

s = keliling∆ : 2
s = (18+24+30) : 2
s = 72 : 2 = 36

L∆ = ½ x AB x AC
L∆ = ½ x 18 x 24
L∆ = 216

jari-jari lingkaran dalam ∆:
r = L/s = 216/36 = 6cm