[填空题]
A reflecting telescope (Fig. Bciakr ozveq y f2b:h0.5o:60jelow) hasb i( -6lxcpdi( a radius of curvature of 3.0 m for its objective mirror and a radiusi6bc (d-(x ipl of curvature of $-1.50m$ for its eyepiece mirror. If the distance between the two mirrors is 0.90 m, how far in front of the eyepiece should you place the photographic film to record the image of a star? $d_{2i}$ = m
