L∆ADC = L∆ABD + 50% L∆ABD
L∆ADC = L∆ABD + ½ L∆ABD
L∆ADC = 3/2 L∆ABD
(a . t)/2 = 3/2 . (a . t)/2
(DC . 8)/2 = 3/2 . (6 . 8)/2
4DC = 36
DC = 36/4
DC = 9 m
Panjang AD:
AD = √82 + 62
AD = √64 + 36
AD = √100
AD = 10 m
Panjang AC:
AC = √82 + 152
AC = √64 + 225
AC = √289
AC = 17 m
Jadi, keliling segitiga = 10 + 17 + 9 = 36 m
2.Amati gambar di samping. Tentukan keliling dan luas daerah yang diarsir. (π = 3,14)
Pembahasan:
Keliling ½ lingkaran = ½ . 2. π . r
= ½ . 2 . 3,14 . 5
= 3,14 . 5
= 15,7 cm