Respostas

2013-12-11T09:39:00-02:00
P=4cm 
p'=12cm 
R=? 

1/f = 1/p + 1/p', logo 1/f = 1/4 + 1/12, logo 1/f = (3+1)/12, logo 1/f = 4/12, logo 1/f = 1/3, logo f=3cm 

Como f=R/2, então 3=R/2, logo R=6cm
1 1 1