Example 23 Find the shortest distance of the point (0, c) from the parabola y = x2,
where 1
2  ≤ c ≤ 5 Solution Let (h, k) be any point on the parabola y = x2 Let D be the required distance
between (h, k) and (0, c) Then
                      
2
2
2
2
D
(
0)
(
)
(
)
h
k
c
h
k
c
=
−
+
−
=
+
−