Answer:
a) Alice moves first, b) Briana finishes the race ahead, c) 
Step-by-step explanation:
a) Alice gets underway first, since the binomial under the square root becomes zero when
, while Alice starts at
.
b) The moment each runner crosses the finish line is:
Alice


Briana



Briana reaches the finish before Alice.
c) Alice and Briana are at the same point when
. From here:



The roots of the polynomial are:
and 
Only the second root is relevant, as they must be parallel at some point prior to finishing the race.