; ; ; ;
EG=KA+AO+OB+BL;KA=h2/S1; BL= h2/S2;
EG=h2/r1+h2/r2+ h2/S1+ h2/S2=U1/U2; U1=c/n1; U2=c/n2
(h2/r1+h2/r2)=1/S1+1/r1+1/S2+1/r2=n2/n1(1/r1+1/r2);
1/S1+1/S2=(n2/n1-1)(1/r1+1/r2);
1/d+1/f=1/F=(n2/n1-1)(1/r1+1/r2);
r1,r2>0 - выпуклая
r1,r2<0 – вогнутая
d=x1+F; f =x2+F;x1x2=F2;