jika perbesaran banyangan yg terbentuk 2 kali bendanya, berapah jarak fokus cermin ? tolong kak pentng :(

Dik: M = 2
        s = 30 cm

M = s'/s
s' = Ms
   = 2 x 30
   = 60 cm

1/f = 1/s + 1/s'
1/f = 1/30 + 1/60
1/f = 2/60 + 1/60
1/f = 3/60
1/f = 1/20
f = 20 cm

maka jarak fokus = 20 cm

semoga bermanfaat