tolong bantu dong kak

Pelajaran : Matematika
Kelas VIII
Materi : lingkaran

Lihat lampiran dibawah ya ^_^
Semoga bermanfaat :D

13. keliling lingkaran 1 (r=10)
= 2πr = 2 x 3,14 x 10 = 62,8 cm
#keliling lingkaran 2 (r=7)
= 2πr = 2 x 22/7 x 7 = 44 cm
#keliling total = kliling 1 + kliling 2
= 62,8 + 44 = 106,8 cm

#luas lngkrn 1 (r=10)
= πr² = 3,14 x 10² = 314 cm²
#L prsgi pnjng - L lngkrn (r=7)
= (14 x 20) - (22/7 x 7²)
= 280 - 154 = 126 cm²
#luas total = 314 + 126 = 440 cm²

14. keliling 1/2 lingkaran 1 (r=28)
=(1/2)2πr = 22/7 x 28 = 88 cm
#keliling lingkaran 2 (r=14)
= 2πr = 2 x 22/7 x 14 = 88 cm
#kliling total = kliling 1 + keliling 2
= 88 + 88 = 176 cm

#luas 1/2 lingkaran 1 (r=14)
=(1/2)πr²=(1/2)(22/7)x 14²= 308 cm²
#L1/2lngkrn(r=28) - L1/2lngkrn(r=14)
= (1/2)(22/7) x 28² - (1/2)(22/7) x 14²
= 1232 - 308 = 924 cm²
#luas total = 924 + 308 = 1232 cm²

semoga membantu ^^

(cek lagi ya siapa tau ada yg salah hitung) :D