Deflection of light 6 the lens equation figure 13.4 and the small-angle approximation imply that da-d,β+d (equation 13.12), where δ~4gm/r: agm/b (equation 13.11) and b~ 0,0 (from the diagram). the summary claims that together these imply that (13.13r) for the angle θ of images formed by a gravitational lens. exercise 13.6.1. verify that this is true. exercise 13.6.2. the solutions to this equation are b b+40 the, solution isclearlyoutside the instein ring angle θε. show that le is meaning that the 0, solution is inside the ring. (hint: argue that 0 s o, and then use this information in equation 13.13, above.)