- Usual surface area (2 exercices)
- Intersection of a surface and a plane (8 exercices)
- Volume (1 exercice)
- Annales - Study of surfaces (1 exercice)
- Annales - Surfaces and arithmetic (5 exercices)
- Annales - Volume (2 exercices)
Figure no1Figure no2Figure no3Figure no4
O−i−j−k
E.4114
In
the
space
equipped
with
an
orthonormal
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
,
we
consider
the
points
:
A
1
;
3
;
2
;
B
4
;
6
;
−
4
and
the
cone
(Γ)
with
axis
O
;
−→
k
,
with
vertex
O
and
con-taining
the
point
A
.
1
Show
that
an
equation
of
(Γ)
is
:
x
2
+
y
2
=
5
2
·
z
2
2
Let
(
P
)
be
the
plane
parallel
to
the
plane
(
xOy
)
and
containing
the
point
B
.
a
Determine
an
equation
of
(
P
)
.
b
Specify
the
nature
of
the
intersection
(
C
1
)
of
(
P
)
and
(Γ)
.
E.4117
In
space
provided
with
the
orthonormal
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
,
note
S
the
surface
of
equa-tion
:
z
=
x
2
+
2
·
x
+
y
2
+
1
Say
if,
yes
or
no,
ˇ
the
section
of
S
with
the
plane
of
equa-tion
z
=5
is
a
circle
of
center
A
of
coordinates
−
1
;
0
;
5
and
radius
5
ı.
E.4138
Space
is
provided
with
an
or-thonormal
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
.
Surface
study
S
equation
z
=
−
1
4
·
x
·
y
1
We
cut
S
through
the
plane
(
xOy
)
.
Determine
the
sec-tion
obtained.
2
We
cut
S
by
a
plane
P
parallel
to
the
plane
(
xOy
)
.
What
is
the
nature
of
the
section
obtained?
3
In
this
question,
any
trace
of
research,
however
incom-plete,
or
initiative,
however
unsuccessful,
will
be
taken
into
account
in
the
assessment.
We
cut
S
by
the
plane
with
equation
x
+
y
=0
.
What
is
the
nature
of
the
resulting
cross-section?
E.4135
In
the
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
,
S
is
the
surface
of
equation
:
4
·
z
=
x
·
y
.
The
following
figures
show
the
intersections
of
S
with
certain
planes
of
space.
1
S
1
denotes
the
section
of
the
surface
S
through
the
plane
(
xOy
)
.
One
of
the
figures
given
represents
S
1
which
one?
2
S
2
designates
the
section
of
S
by
the
plane
R
of
equation
z
=1
.
One
of
the
given
figures
represents
S
2
,
which
one?
3
S
3
denotes
the
section
of
S
through
the
plane
of
equation
y
=8
.
One
of
the
figures
given
represents
S
3
,
which
one?
E.4136
For
each
of
the
following
questions,
indicate
whether
the
proposed
statement
is
true
or
false
and
justify
the
answer.
Space
is
provided
with
an
orthonormal
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
.
1
E
is
the
set
of
points
M
space
whose
coordinates
(
x
;
y
;
z
)
verify
the
equation
:
z
=
x
2
+
y
2
.
Note
S
the
section
of
E
by
the
plane
of
equation
y
=
3
.
Assertion:
S
is
a
circle.
2
P
is
the
surface
of
equation
x
2
+
y
2
=3
·
z
2
Assertion:
O
is
the
only
point
of
intersection
of
P
with
the
plane
(
yOz
)
with
integer
coordinates.
E.4311
Space
is
provided
with
an
orthonor-mal
reference
frame
O
;
−→
i
;
−→
j
;
−→
k
.
Consider
the
surface
S
,
one
equation
of
which
is
:
z
=
4
·
x
·
y
Show
that
the
section
of
the
surface
S
through
the
plane
of
equation
z
=0
is
the
union
of
two
orthogonal
straight
lines.
3.
Volume
E.4140
For
each
of
the
following
two
propositions,
indicate
whether
it
is
true
or
false
and
give
a
demonstration
of
the
chosen
answer.
An
unproven
answer
scores
no
points.
Space
is
referred
to
an
orthonormal
refer-ence
frame
O
;
−→
i
;
−→
j
;
−→
k
.
The
surface
Σ
opposite
has
the
equation
:
z
=
x
2
+
y
2
1
The
section
of
the
surface
Σ
and
the
plane
of
equation
x
=
–
,
where
–
is
a
real,
is
a
hyperbola.
2
The
plane
of
equation
z
=
9
·
2
2
di-vides
the
solid
bounded
by
Σ
and
the
plane
of
equation
z
=9
into
two
solids
of
equal
volume.
Reminder.
Let
V
be
the
volume
of
the
solid
bounded
by
Σ
https://chingmath.fr
chapExoCorrec/4114
sacados/4114
chapExoCorrec/4117
sacados/4117
chapExoCorrec/4138
sacados/4138
Extrait d'Ameriques du Sud
Novembre 2008
chapExoCorrec/4135
sacados/4135
Extrait Centres Etrangers
Juin 2009
Figure no1Figure no2Figure no3Figure no4
chapExoCorrec/4136
sacados/4136
Extrait d'Antilles-Guyanes
Juin 2009
sacados/4311
chapExoCorrec/4140
sacados/4140
Extrait de Liban
Mai 2008
O−i−j−k
Figure no1Figure no2Figure no3
and
the
planes
of
equations
z
=
a
and
z
=
b
where
0
a
b
9
.
V
is
given
by
the
formula
V
=
b
a
S
(
k
)
d
k
where
S
(
k
)
is
the
cross-sectional
area
of
the
solid
through
the
plane
of
equation
z
=
k
where
k
∈
a
;
b
.
4.
Annales
-
Study
of
surfaces
E.4143
The
space
(
E
)
is
equipped
with
an
orthonormal
basis
O
;
−→
i
;
−→
j
;
−→
k
.
Consider
the
points
:
A
0
;
5
;
5
;
B
0
;
0
;
10
1
In
this
question,
we
are
working
in
the
plane
P
0
with
equation
x
=
0
relative
to
the
coordinate
system
O
;
−→
i
;
−→
j
.
Let
C
be
the
circle
with
center
B
and
passing
through
A
.
Prove
that
the
line
(
OA
)
is
tangent
to
the
circle
C
.
2
We
call
S
the
sphere
generated
by
the
rotation
of
the
circle
C
around
the
axis
(
Oz
)
and
Γ
the
cone
generated
by
the
rotation
of
the
line
(
OA
)
around
the
axis
(
Oz
)
.
a
Prove
that
the
cone
Γ
has
the
equation
:
x
2
+
y
2
=
z
2
b
Determine
the
intersection
of
the
cone
Γ
and
the
sphere
S
.
Specify
the
nature
of
this
intersection
and
its
charac-
teristic
elements.
c
Illustrate
these
objects
with
a
diagram
in
space.
3
We
cut
the
cone
Γ
by
the
plane
P
1
with
equation
x
=1
.
In
P
1
,
one
of
the
three
figures
below
represents
this
in-tersection.
Identify
this
figure
and
provide
the
necessary
justifica-tion.
4
Let
M
(
x
;
y
;
z
)
be
a
point
on
the
cone
Γ
whose
coordi-nates
are
non-zero
relative
integers.
Prove
that
x
and
y
cannot
both
be
odd.
5.
Annales
-
Surfaces
and
arithmetic
E.4087
Part
A
Consider,
in
a
coordinate
system
O
;
−→
i
;
−→
j
;
−→
k
in
space,
the
surface
S
with
equation
:
z
=
x
−
y
)
2
1
We
denote
E
1
the
intersection
of
S
with
the
plane
P
1
of
equation
z
=0
.
Determine
the
nature
of
E
1
.
2
We
note
E
2
the
intersection
of
S
with
the
plane
P
2
of
equation
x
=1
.
Determine
the
nature
of
E
2
.
Part
B
Consider,
in
a
coordinate
system
O
;
−→
i
;
−→
j
;
−→
k
in
space,
the
surface
S
with
equation
:
z
=
x
·
y
1
We
note
E
3
the
intersection
of
S
with
the
plane
P
1
of
equation
z
=0
.
Determine
the
nature
of
E
3
.
2
We
note
E
4
the
intersection
of
S
with
the
plane
P
3
of
equation
z
=1
.
Determine
the
nature
of
E
4
.
Part
C
Let
E
5
be
the
intersection
of
S
and
S
.
In
this
section,
we
want
to
show
that
the
only
point
belong-ing
to
E
5
whose
coordinates
are
natural
numbers
is
the
point
O
0
;
0
;
0
.
We
assume
that
there
is
a
point
M
belonging
to
E
5
and
whose
coordinates
x
,
y
and
z
are
natural
integers.
1
Show
that
if
x
=0
,
then
the
point
M
is
the
point
O
2
We
now
assume
that
the
integer
x
,
y
and
z
vérifient
:
x
2
−
3
·
x
·
y
+
y
2
=
0
.
Deduce
that
there
then
exist
natural
numbers
x
and
y
premiers
between
them
such
that
:
x
2
−
3
·
x
·
y
+
y
2
=
0
3
Show
that
x
divides
y
2
,
then,
that
x
divise
y
.
4
Establish
that
y
verify
the
relationship
:
1
−
3
·
y
+
y
2
=
0
5
Conclude.
https://chingmath.fr
chapExoCorrec/4143
sacados/4143
Pondichery
Avril 2004
Figure no1Figure no2Figure no3
chapExoCorrec/4087
sacados/4087
Pondichery
Avril 2011
5 points
E.4132
The
space
is
equipped
with
an
orthonor-mal
basis
O
;
−→
i
;
−→
j
;
−→
j
.
We
consider
the
surface
S
1
of
equation
z
=
x
2
+
y
2
and
the
surface
S
2
of
equation
z
=
x
·
y
+2
·
x
Part
A
Let
P
be
the
plane
of
equation
x
=2
,
E
1
the
intersection
of
the
surface
S
1
and
the
plane
P
and
E
2
the
intersection
of
the
surface
S
2
and
the
plane
P
.
In
the
appendix,
the
plane
P
is
marked
with
the
reference
A
;
−→
i
;
−→
j
where
A
is
the
point
with
coordinates
2
;
0
;
0
.
1
a
Determine
the
nature
of
the
set
E
1
.
b
Determine
the
nature
of
the
set
E
2
.
2
a
Represent
the
sets
E
1
and
E
2
on
the
sheet
ap-pendix
.
b
In
the
reference
point
O
;
−→
i
;
−→
j
;
−→
k
give
the
coordi-nates
of
the
points
of
intersection
B
and
C
of
the
sets
E
1
and
E
2
.
Part
B
The
following
property
can
be
used
without
proof
:
ˇLet
a
,
b
and
c
be
integers
with
a
prime.
If
a
divides
b
·
c
then
a
divides
b
or
a
divides
c
.
ı
The
objective
of
this
section
is
to
determine
the
points
of
in-tersection
M
(
x
;
y
;
z
)
of
the
surfaces
S
1
and
S
2
where
y
and
z
are
relative
integers
and
x
is
a
prime
integer.
We
consider
such
a
point
M
(
x
;
y
;
z
)
.
1
a
Show
that
:
y
(
y
−
x
)=
x
(2
−
x
)
.
b
Deduce
that
the
prime
number
x
divides
y
.
2
We
set
y
=
k
·
x
with
k
∈
Z
.
a
Show
that
x
divides
2
,
then
that
x
=2
.
b
Deduce
the
possible
values
of
k
.
3
Determine
the
possible
coordinates
of
M
and
compare
the
results
with
those
in
part
A
question
2
b
.
E.4137
The
space
is
equipped
with
an
orthonormal
basis
O
;
−→
i
;
−→
j
;
−→
k
.
1
Let
F
be
the
point
with
coordinates
0
;
0
;
1
4
and
P
be
the
plane
with
equation
z
=
−
1
4
.
Let
d
(
M;P
)
be
the
distance
from
a
point
M
to
the
plane
P
.
Show
that
the
set
(
S
)
of
points
M
with
coordinates
(
x
;
y
;
z
)
that
satisfy
d
(
M
;
P
)=
MF
a
has
the
equation
:
x
2
+
y
2
=
z
.
2
a
What
is
the
nature
of
the
intersection
of
the
set
(
S
)
with
the
plane
of
equation
z
=2
?
b
What
is
the
nature
of
the
intersection
of
the
set
(
S
)
with
the
plane
of
equation
x
=0
?
Represent
this
intersection
in
the
coordinate
system
O
;
−→
j
;
−→
k
3
In
this
question,
x
and
y
denote
natural
numbers.
a
What
are
the
possible
remainders
of
the
Euclidean
di-vision
of
x
2
by
7
?
b
Prove
that
7
divides
x
2
+
y
2
if,
and
only
if,
7
divides
x
and
7
divides
y
.
4
In
this
question,
any
attempt
at
research,
even
if
incom-plete,
or
any
initiative,
even
if
unsuccessful,
will
be
taken
into
account
in
the
assessment.
Are
there
any
points
that
belong
to
the
intersection
of
the
set
(
S
)
and
the
plane
of
equation
z
=
98
and
whose
coordinates
are
all
natural
numbers?
If
so,
determine
them.
https://chingmath.fr
chapExoCorrec/4132
sacados/4132
chapExoCorrec/4137
sacados/4137
La R&union
Juin 2009
E.4141
In
the
space
equipped
with
an
orthonormal
reference
frame
O
;
−→
i
;
−→
j
;
−→
j
,
we
consider
the
points
A
1
;
3
;
2
and
B
4
;
6
;
−
4
and
the
cone
(Γ)
with
axis
O
;
−→
k
,
with
vertex
O
and
containing
the
point
A
.
Part
A
1
Show
that
an
equation
of
(Γ)
is
:
x
2
+
y
2
=
5
2
·
z
2
2
Let
(
P
)
be
the
plane
parallel
to
the
plane
(
xOy
)
and
containing
the
point
B
,
a
Determine
an
equation
of
(
P
)
.
b
Specify
the
nature
of
the
intersection
(
C
1
)
of
(
P
)
and
(Γ)
.
3
Let
(
Q
)
be
the
equation
plane
y
=3
.
We
note
(
C
2
)
the
intersection
of
(Γ)
and
(
Q
)
.
Without
justification,
iden-tify
the
nature
of
(
C
2
)
from
among
the
following
propo-sitions
:
a
two
parallel
lines
;
b
two
intersecting
lines
;
c
a
parabola;
d
a
hyperbola;
e
a
circle.
Part
B
Let
x
,
y
and
z
be
three
relative
integers
and
M
the
point
with
coordinates
(
x
;
y
;
z
)
.
The
sets
(
C
1
)
and
(
C
2
)
are
the
sections
defined
in
part
A
.
1
Consider
the
equation
(
E
):
x
2
+
y
2
=40
where
x
and
y
are
relative
integers.
a
Solve
the
equation
(
E
)
.
b
Deduce
all
points
of
(
C
1
)
whose
coordinates
are
rela-tive
integers.
2
a
Prove
that
if
the
point
M
with
coordinates
(
x
;
y
;
z
)
where
x
,
y
and
z
denote
relative
integers,
is
a
point
of
(Γ)
then
z
is
divisible
by
2
and
x
2
+
y
2
is
divisible
by
10
.
b
Show
that
if
M
is
a
point
of
(
C
2
)
,
intersection
of
(Γ)
and
(
Q
)
,
then
:
x
2
≡
1
(
mod.
10)
c
Determine
a
point
(
C
2
)
,
distinct
from
A
,
whose
coor-dinates
are
relative
integers.
E.4139
The
space
is
referenced
to
the
orthonormal
coordinate
system
O
;
−→
i
;
−→
j
;
−→
k
.
We
call
(
S
)
the
surface
with
equation
:
x
2
+
y
2
−
z
2
=
1
1
Show
that
the
surface
(
S
)
is
symmetrical
with
respect
to
the
plane
xOy
.
2
We
call
A
and
B
the
points
with
the
respective
coordi-nates
:
3
;
1
;
−
3
;
−
1
;
1
;
1
a
Determine
a
parametric
representation
of
the
line
(
D
)
passing
through
the
points
A
and
B
.
b
Prove
that
the
line
(
D
)
is
included
in
the
surface
(
S
)
.
3
Determine
the
nature
of
the
section
of
the
surface
(
S
)
by
a
plane
parallel
to
the
plane
(
xOy
)
.
4
a
Consider
the
curve
(
C
)
,
the
intersection
of
the
sur-face
(
S
)
and
the
plane
with
equation
z
=
68
.
Specify
the
characteristic
elements
of
this
curve.
b
M
being
a
point
of
(
C
)
,
we
designate
a
as
its
abscissa
and
b
as
its
ordinate.
We
propose
to
show
that
there
is
only
one
point
M
of
(
C
)
such
that
a
and
b
are
natural
integers
satisfying
:
a
<b
;
ppcm
(
a
;
b
)
=
440
.
That
is,
such
that
(
a
;
b
)
is
a
solution
to
the
system
:
(1)
:
a
<b
a
2
+
b
2
=
4625
ppcm
(
a
;
b
)
=
440
Show
that
if
(
a
;
b
)
is
a
solution
of
(1)
then
pgcd
(
a
;
b
)
is
equal
to
1
or
to
5
.
Conclude.
In
this
question
any
trace
of
research,
even
if
incom-plete,
or
initiative,
even
if
unsuccessful,
will
be
taken
into
account
in
the
assessment.
6.
Annales
-
Volume
E.4199
The
space
(
E
)
is
equipped
with
an
orthonormal
basis
O
;
−→
i
;
−→
j
.
We
consider
the
surface
T
with
equation
:
x
2
·
y
=
z
with
−
1
x
1
and
−
1
y
1
.
The
figure
opposite
is
a
representation
of
the
surface
T
in
the
cube
with
center
O
and
side
length
2
.
1
Elements
of
symmetry
of
the
surface
T
.
a
Show
that
if
point
M
(
x
;
y
;
z
)
belongs
to
T
,
then
point
M
(
−
x
;
y
;
z
)
also
belongs
to
T
.
Deduce
a
plane
of
symmetry
of
T
.
b
Show
that
the
origin
O
of
the
coordinate
system
is
the
center
of
symmetry
of
T
.
2
Intersections
of
the
surface
T
with
planes
parallel
to
the
axes.
a
Determine
the
nature
of
the
intersection
curves
of
T
with
planes
parallel
to
the
plane
(
xOz
)
.
b
Determine
the
nature
of
the
intersection
curves
of
T
with
planes
parallel
to
the
plane
(
yOz
)
.
3
Intersections
of
the
surface
T
with
planes
parallel
to
the
plane
(
xOy
)
of
equations
z
=
k
,
avec
k
∈
0
;
1
.
a
Determine
the
intersection
of
the
surface
T
and
the
plane
of
equation
z
=0
.
b
For
k>
0
,
we
note
K
the
point
with
coordinates
0
;
0
;
k
.
Determine,
in
the
coordinate
system
K
;
−→
i
;
−→
j
,
the
equation
of
the
intersection
curve
of
T
and
the
plane
with
equation
z
=
k
.
c
Draw
the
shape
of
this
curve
in
the
coordinate
system
K
;
−→
i
;
−→
j
.
Specify
in
particular
the
coordinates
of
the
endpoints
of
the
arc.
https://chingmath.fr
chapExoCorrec/4141
sacados/4141
Polynesie
Juin 2007
chapExoCorrec/4139
sacados/4139
Ameriques du Nord
Mai 2008
chapExoCorrec/4199
sacados/4199
4
We
denote
(
D
)
the
domain
formed
by
the
points
of
the
unit
cube
located
below
the
surface
T
:
(
D
)=
M
(
x
;
y
;
z
)
∈
(
E
)
⏐
⏐
⏐
0
x
1
;
0
y
1
;
0
z
x
2
·
y
a
For
0
<k
1
,
the
plane
of
equation
z
=
k
coupe
the
do-main
(
D
)
selon
a
surface
that
can
be
visualized
on
the
graph
in
question
3
c
.
This
is
the
set
of
points
M
of
the
unit
cube
with
coor-dinates
(
x
;
y
;
z
)
such
as
:
y
k
x
2
et
z
=
k
.
Calculate
as
a
function
of
k
the
area
S
(
k
)
expressed
in
units
of
area
of
this
surface.
b
We
pose
S
(0)=1
;
calculate
in
units
of
volume,
the
volume
V
du
domain
(
D
)
.
Recall
that
:
V
=
1
0
S
(
k
)
dk
.
E.4319
Part
A
:
Organized
knowledge
retrieval
1
Prerequisite
:
any
integer
n
strictly
greater
than
1
has
at
least
one
prime
divisor.
Prove
that
every
integer
n
strictly
greater
than
1
is
prime
or
can
be
decomposed
into
a
product
of
prime
factors
(we
do
not
ask
you
to
prove
the
uniqueness
of
this
decompo-sition)
.
2
Give
the
decomposition
into
prime
factors
of
629
.
Part
B
In
an
orthonormal
coordinate
system
O
;
−→
i
;
−→
j
;
−→
k
,
we
consider
the
surfaces
Γ
and
C
with
respective
equations
:
Γ
:
z
=
x
·
y
;
C
:
x
2
+
z
2
=
1
1
Give
the
nature
of
the
surface
C
and
determine
its
char-acteristic
elements.
2
Points
of
intersection
with
integer
coordinates
of
surfaces
Γ
and
C
.
a
Show
that
the
coordinates
(
x
;
y
;
z
)
of
the
intersection
points
of
Γ
and
C
are
such
that
:
x
2
·
1
+
y
2
=
1
b
Deduce
that
Γ
and
C
have
two
points
of
intersection
whose
coordinates
are
relative
integers.
3
Points
of
intersection
with
integer
coordinates
of
Γ
and
a
plane.
For
any
non-zero
natural
number
n
,
we
denote
by
P
n
the
plane
of
equation
z
=
n
4
+4
a
Determine
the
set
of
intersection
points
of
Γ
and
the
plane
P
1
whose
coordinates
are
relative
integers.
for
the
rest
of
the
exercise,
we
assume
n
2
.
b
Check
that
:
n
2
−
2
·
n
+
2
n
2
+
2
·
n
+
2
=
n
4
+
4
c
Prove
that,
regardless
of
the
natural
number
n
2
,
the
integer
n
4
+4
is
not
prime.
d
Deduce
that
the
number
of
points
of
intersection
of
Γ
and
the
plane
P
n
whose
coordinates
are
relative
inte-gers
is
greater
than
or
equal
to
8
.
e
Determine
the
points
of
intersection
of
Γ
and
the
plane
P
5
whose
coordinates
are
relative
integers.
https://chingmath.fr
sacados/4319
Asie
Juin 2011
5 points