In Figure let the angle of the two rays be 20.0o, slit separation d be 58.00m, and

In Figure let the angle θ of the two rays be 20.0o, slit separation d be 58.00μm, and wavelength λ be 500.9 nm.
(a) What multiple of λ gives the phase difference of the two rays when they reach a common point on a distant screen?
(b) Does their interference result in complete darkness, maximum brightness, intermediate illumination but closer to complete darkness, or intermediate illumination but closer to maximum brightness?