k
=
k =
k
=
5
Level curves are sets of points
(
x
,
y
)
(x,y)
(
x
,
y
)
where
f
(
x
,
y
)
=
k
f(x,y) = k
f
(
x
,
y
)
=
k
, for some chosen constant number
k
k
k
.
When we lift the level curves up onto the graph, we get "horizontal traces."