Hope this helps you with your questions.
Answer:

Step-by-step explanation:
A bisector is the line that divides an angle (which in this case is
) exactly in half. Therefore,
and as such we can solve for
:

and we are done.
Answer:
Use this formula for these kinda things.
Step-by-step explanation:
Remember The z is the hypathonous, it means the biggest side.

where Z is going to be C
put this all together

put it into calculator, means 373=

therfore take the square root, it will be

which it will be 19.31
By definition, an isolated point x of a set S is a point of S.
Also, an interior point of a set S can be defined by the mean of the
existence of a positive number r>0 such that :

wherein D(x,r) is the disc of center x and radius r.
Example of a set whose boundary is not a subset of S: