Jawabanmu

2014-06-02T20:08:18+07:00
R=a.b.c:4L
21x28x35: 4( 1/2 x 28 x 21)
20580 : 1176 =17.5
2014-06-02T20:11:25+07:00
Cari dulu sisi AC
AC = √BC² - AB²
AC = √35² - 21²
AC= √1225 - 441
AC = √784 = 28 CM

r = a.b.c/4L.segitiga
r = 21 x 35 x 28/4 x (21x28/2)
r = 20580/4 x 294
r = 20580/1176
r = 17.5