At t $0,$ a bright beacon at the origin flashes, sending light uniformly in all directions. Anna is moving at speed v in the x direction relative to the beacon and passes through the origin at t $0.($a$)$ Show that according to Anna, the only light with a positive x$-$component is that which in the beacon$$s reference frame is within an angle cos$1($v$/$c$)$ of the x$-$axis. $($b$)$ What are the limits of as v approaches $0$ and as it approaches c$?($c$)$ The phenomenon is called the headlight effect. Why?