Answer:
Part 12)
Part 13)
Explanation:
Part 12) we know that
The equation of a circle in center-radius form is equal to
where
(h,k) is the center of the circle
r is the radius of the circle
In this problem
Looking at the graph
The center is the
The radius is
substitute in the expression above
Part 13) we know that
The measure of the external angle is the semi-difference of the arcs it covers.
so
we have