- Isometry (14 exercices)
- Isometry compound (2 exercices)
MNIJ
ABCDE
OPI(dNM(dNMCC
ABG
E.2632
A
road
is
to
be
built
from
town
M
to
town
N
.
This
road
has
to
pass
over
a
river:
the
bridge
will
be
perpen-dicular
to
the
riverbed.
Place
the
bridge
(more
precisely
the
points
I
and
J
)
so
that
the
length
of
the
road
is
minimal.
Hint
:
think
of
the
triangular
inequality.
E.2645
Consider
the
five
points
of
the
plane
shown
below
:
1
Determine
the
center
and
ratio
of
the
homothety
trans-forming
A
into
C
and
B
into
D
.
2
Determine
the
center
of
the
homothety
of
ratio
3
2
trans-forming
the
point
B
into
the
point
A
.
3
Justify
that
there
are
no
homotheties
transforming
B
into
C
and
D
into
E
.
E.2646
Consider
two
points
in
the
plane
O
and
P
separated
by
1
cm
;
the
circle
C
has
the
point
O
as
its
cen-ter
and
a
radius
of
3
cm
;
the
circle
C
has
center
P
and
radius
2
cm
.
Let
I
be
the
point
of
intersection
of
the
straight
line
(
OP
)
with
the
circle
C
.
The
straight
line
(
d
)
passing
through
I
intercepts
the
circles
C
and
C
at
M
and
N
respectively.
The
straight
line
(
d
)
passing
through
I
is
secant
to
the
circle
C
at
M
and
also
intersects
the
circle
C
at
N
.
1
Show
that
the
point
I
also
belongs
to
the
circle
C
.
What
can
you
tell
from
the
relative
position
of
the
two
circles
C
and
C
.
2
Determine
the
center
and
ratio
of
the
homothety
trans-forming
the
circle
C
into
the
circle
C
.
3
Deduce
that
the
straight
lines
(
NN
)
and
(
MM
)
are
parallel.
E.573
Let
C
be
a
circle
of
center
O
and
A
a
point
of
the
circle.
Consider
the
point
M
running
through
the
circle
C
and
I
the
middle
of
the
segment
[
OM
]
What
does
the
point
I
describe
when
the
point
M
describes
the
circle
C
?
E.574
Construct,
in
the
figure
below,
the
point
C
such
that
ABC
has
as
center
of
the
inscribed
circle
(the
point
of
intersection
of
the
bisectors)
the
point
G
.
https://chingmath.fr
chapExoCorrec/2632
sacados/2632
MNIJ
chapExoCorrec/2645
sacados/2645
ABCDE
chapExoCorrec/2646
sacados/2646
OPI(dNM(dNMCC
chapExoCorrec/573
sacados/573
chapExoCorrec/574
sacados/574
ABG
AMOC
ABMNIC
MNIJ
OABCD
E.1839
Consider
a
circle
C
,
a
point
A
∈
C
and
a
point
M
that
describes
the
circle:
i.e.
the
position
of
M
is
variable
and
it
will
travel
the
circle
C
.
Consider
the
point
I
middle
of
[
AM
]
.
1
Place
the
point
I
on
the
figure
above.
2
a
Place
the
point
M
diametrically
opposite
the
point
A
.
Where
then
is
the
point
I
.
b
If
the
point
M
lies
in
A
,
where
is
the
point
I
.
c
Place
the
point
M
at
four
other
possible
locations
and
construct
the
associated
point
I
each
time
3
When
the
point
M
describes
the
entire
circle
C
which
set
describes
the
point
I
.
E.1852
Consider
a
circle
C
of
diameter
[
AB
]
.
Let
M
and
N
be
two
points
of
C
distinct
from
A
and
B
.
1
Place
on
the
figure
above
the
point
J
intersection
of
the
straight
lines
(
NB
)
and
(
MA
)
.
2
Show
that
the
straight
line
(
IJ
)
is
perpendicular
to
(
BA
)
.
E.1854
A
road
is
to
be
built
from
town
M
to
town
N
.
This
road
has
to
pass
over
a
river:
the
bridge
will
be
perpen-dicular
to
the
riverbed.
Place
the
bridge
(more
precisely
the
points
I
and
J
)
so
that
the
length
of
the
road
is
minimal.
Hint
:
think
of
the
triangular
inequality.
E.1869
Consider
the
two
triangles
OCD
and
OAB
rectangles
isosceles
at
O
By
means
of
a
rotation,
the
characteristics
of
which
will
be
indicated,
show
that
the
segments
[
CA
]
and
[
DB
]
have
the
same
length.
https://chingmath.fr
chapExoCorrec/1839
sacados/1839
AMOC
sacados/1852
ABMNIC
chapExoCorrec/1854
sacados/1854
MNIJ
chapExoCorrec/1869
sacados/1869
OABCD
ABCDEF
ABCMM1M2M
E.1870
Consider
a
rectangle
ABCD
,
M
a
point
on
[
DC
]
,
and
N
a
point
on
[
BC
]
.
Determine,
in
the
figure
above,
the
positions
of
points
M
and
N
such
that
the
path
passing
through
points
E
,
M
,
N
,
and
F
is
as
short
as
possible.
(No
justification
is
required)
.
2.
Isometry
compound
E.2631
Let
A
,
B
,
C
be
three
distinct
two-by-two
points
in
the
plane
and
M
be
any
point
in
the
plane.
The
figure
opposite
represents
the
image
M
of
M
by
the
transformation
SCOPY
01
S
B
◦
S
A
where
:
S
A
(
M
)
=
M
1
;
S
B
(
M
1
)
=
M
2
;
S
C
(
M
2
)
=
M
Determine,
if
they
exist,
the
invariants
of
the
transformation
S
C
◦
S
B
◦
S
A
.
E.2633
Consider
in
the
plane
a
square
ABCD
.
Let
I
be
the
midpoint
of
[
AB
]
.
1
Simplify
the
writing
of
the
following
transformation
:
t
−−→
AB
◦
t
−→
CA
◦
t
−→
AC
◦
t
−−→
BC
2
Establish
the
following
relationship
:
t
−−→
BC
◦
S
I
◦
S
B
=
t
−−→
BD
3
Determine
the
point
M
verifying
the
following
relation-ship
:
S
I
◦
S
B
=
S
M
◦
S
C
https://chingmath.fr
chapExoCorrec/1870
sacados/1870
ABCDEF
chapExoCorrec/2631
sacados/2631
ABCMM1M2M
chapExoCorrec/2633
sacados/2633