Jika keliling = 36 cm. Hitungan x dan luasnya ! pake cara

36 = 8 + 13 + x
x = 36 - 21 = 15

s=1/2.(a+b+c)=1/2.(36)=18
luas = √((s)(s-a)(s-b)(s-c))
=√((18)(18-8)(18-13)(18-15))
=√((18)(10)(5)(3))
=√(2700)
=30√3

x = 36 - (13+8)
= 15 cm

s = K/2 = 36/2 = 18 cm

L=√[s(s-a) (s-b) (s-c)]
=√[18(18-13)(18-15)(18-8)]
=√[18.5.3.10]
=√2700
=√[900.3] = 30√3 cm