## University Physics with Modern Physics (14th Edition)

The angle $\theta=\frac{28 km}{1200km}$. Use Rayleigh’s criterion, $sin \theta_1=1.22\frac{\lambda}{D}$. $$D =1.22\frac{\lambda}{ sin \theta_1}$$ The angle is small, so $sin \theta \approx \theta$. $$D =1.22 (3.6 cm) \frac{1200km}{28 km}=188 cm$$