Resolving Power and diffraction

[Dart82]

Homework Statement

Late one night on a highway, a car speeds by you and fades into the distance. Under these conditions the pupils of your eyes (average refractive index = 1.36) have diameters of about 7.0 mm. The taillights of this car are separated by a distance of 1.3 m and emit red light (wavelength = 660 nm in vacuum). How far away from you is this car when its taillights appear to merge into a single spot of light because of the effects of diffraction?
[URL=http://img58.imageshack.us/my.php?image=resolvingpoweruz3.jpg][PLAIN]http://img58.imageshack.us/img58/1871/resolvingpoweruz3.th.jpg[/URL][/PLAIN]

Homework Equations

s=r(theta)
Rayleigh criterion for resolution: theta min = 1.22 (lambda/D)

The Attempt at a Solution

lambda eye = lambda vacuum/ n eye
(660x10^-9m) / 1.32 = 5x10^-7m

1.22(lambda eye/D)=s/r
1.22(5x10^-7m)/0.007m = 1.3m/r
r = 15385 meters
What am i doing wrong here??

 

[malawi_glenn]

the answer should be?

 

[Dart82]

the only thing i can think of is:
a^2 + b^2 = c^2

(15385m^2) - (.65m^2 ) = answer ...i got 15384.99 which i know isn't right