Eclipsing Binaries

(Quick question.) Sketch (roughly to scale) schematic light curves of the following types of binaries. A light curve is a graph of total light intensity against time, similar to Fig. 10.5 in Shu.

1. Small, bright star A and large, dim star B. The diameter and brightness of A are one third and twice the diameter and brightness of B respectively. Both A and B are perfect spheres. Eclipses are total.
2. Two stars A and B of equal diameter and brightness. Both A and B have tidal bulges. Eclipses are total.

Suppose our Sun acquired a twin star of equal mass and diameter, forming a binary with a circular, 5-yr orbit. Let us call the system `the Solar binary'.

3. What is the semimajor axis of the Solar binary?
4. Suppose Zog is an alien observer on some other star. In order for Zog to see the Solar binary as an eclipsing binary, what is the minimum inclination angle i of her line of sight with respect to the perpendicular of the orbital plane of the Solar Binary?