- Angles and trigonometry (7 exercices)
- Angles and isosceles triangles (3 exercices)
- Angles and right-angled triangles (1 exercice)
- Angles and thales (2 exercices)
- Small and large bows (2 exercices)
- A little of everything (2 exercices)
CABCOHE
OCNBAM80o25oC
OMBAI20oC
OIJKC
E.5406
The
figure
below
is
not
to
be
repeated
on
the
copy.
It
is
not
given
in
full
size.
A
,
B
and
C
are
three
points
on
a
circle
C
(see
fig-ure)
.
We
know
that
AB
=3
cm
,
the
height
[
AH
]
measures
2.5
cm
.
We
trace
the
diameter
[
AE
]
.
1
What
is
the
nature
of
the
triangle
ACE
?
Justify
the
answer.
2
Explain
why
the
angles
ABC
and
AEC
are
equal.
3
Using
the
triangle
ABH
,
calculate
the
exact
value
of
sin
ABH
and
deduce
the
measure
of
the
angle
AEC
rounded
to
the
nearest
degree.
2.
Angles
and
isosceles
triangles
E.800
The
points
A
,
B
,
C
,
M
and
N
belong
to
the
cir-cle
C
of
center
O
verify-ing
the
measures
:
AOB
=80
o
;
BNC
=25
o
1
Calculate
the
mea-sure
of
AMB
.
2
Calculate
the
mea-sure
of
each
angle
of
triangle
BOC
.
3
Deduce
the
measure
of
each
of
the
angles
AOC
and
AMC
.
E.802
Let
C
be
a
circle
of
center
O
.
A
,
B
,
M
three
points
of
the
circle
such
that
ABM
=20
o
.
Let
I
be
the
middle
of
seg-ment
[
AB
]
.
Calculate
the
value
of
the
an-gle
AOB
.
Justify.
E.5405
The
figure
opposite
is
not
full-scale
;
we
do
not
ask
you
to
re-produce
it.
Consider
a
circle
C
with
center
O
and
diameter
8
cm
.
I
and
J
are
two
diametrically
opposed
points.
K
is
a
point
of
C
such
that
JK
=4
cm
.
1
a
Specify
the
nature
of
the
triangle
OJK
.
Justify.
b
Deduce
the
measure
of
the
angle
JIK
.
Justify
your
answer.
2
a
Specify
the
nature
of
the
triangle
IJK
.
Justify.
b
Give
the
measurement,
to
the
nearest
millimetre,
of
segment
[
IK
]
.
3
We
call
R
the
image
of
K
by
symmetry
of
axis
(
IJ
)
.
Demonstrate
that
the
quadrilateral
ROKJ
is
a
rhombus.
3.
Angles
and
right-angled
triangles
E.4338
Consider
the
figure
below,
which
is
not
full-scale.
It
is
not
necessary
to
redo
the
figure.
https://chingmath.fr
chapExoCorrec/5406
sacados/5406
Brevet de Reims
Septembre 2002
CABCOHE
chapExoCorrec/800
sacados/800
OCNBAM80o25oC
chapExoCorrec/802
sacados/802
OMBAI20oC
chapExoCorrec/5405
sacados/5405
OIJKC
chapExoCorrec/4338
sacados/4338
Pondichery
Avril 2011
ABDOMC75o
ABCOHC(d
ABDEC
BDACC
ABD
is
an
isosceles
tri-angle
at
A
such
that
:
ABD
=75
o
;
C
is
the
circumscribed
circle
of
the
triangle
ABD
;
O
is
the
center
of
the
cir-cle
C
;
[
BM
]
is
a
diameter
of
C
.
1
What
is
the
nature
of
the
triangle
BMD
?
Justify
the
answer.
2
a
Calculate
the
measure
of
the
angle
BAD
.
b
Name
an
inscribed
angle
that
intercepts
the
same
arc
of
the
circle
C
as
the
angle
BMD
.
c
Justify
that
the
angle
BMD
measures
30
o
.
3
We
give
:
BD
=5.6
cm
;
BM
=11.2
cm
Calculate
DM
.
Round
the
result
to
the
nearest
tenth.
4.
Angles
and
thales
E.805
The
figure
opposite
is
not
made
to
actual
dimensions.
Let
C
be
a
circle
of
center
O
radius
6
cm
.
Points
A
and
C
are
diametri-cally
opposed.
B
is
a
point
on
the
circle
such
that
BC
=3
cm
.
The
segment
[
BC
]
measures
3
cm
in
length.
The
line
(
d
)
is
perpendicular
to
(
BC
)
passing
through
the
point
O
.
It
intersects
segment
[
BC
]
at
H
.
1
What
is
the
nature
of
the
triangle
ABC
?
Justify.
2
Determine
the
measure
of
the
angle
BAC
.
3
a
Determine
the
measure
of
the
angle
BOC
.
Justify
b
What
is
the
nature
of
the
triangle
OBC
?
Justify
c
Deduce
the
measure
of
the
angle
BOH
d
Justify
the
fact
that
:
BH
=1.5
cm
.
4
Calculate
the
value
of
OH
to
the
nearest
millimetre.
E.3928
On
the
figure
opposite,
which
is
not
full-scale,
we
know
that
:
(
C
)
est
a
circle
with
center
E
dont
the
diameter
[
AD
]
mesure
9
cm
.
B
is
a
point
of
circle
C
such
that
:
AEB
=46
o
1
Make
the
figure
respecting
the
given
dimensions.
2
Show
that
the
triangle
ABD
is
a
right-angled
triangle.
3
Justify
that
:
ADB
=
23
o
.
4
Calculate
the
length
AB
and
specify
its
value
rounded
to
the
hundredth
of
cm
.
5
Draw
the
line
parallel
to
the
line
(
AB
)
passing
through
E
.
It
intersects
segment
[
BD
]
at
point
F
.
Place
the
point
F
.
6
Calculate
the
length
EF
and
specify
its
value
rounded
to
the
tenth
of
cm
.
5.
Small
and
large
bows
E.2938
Consider
a
quadrilateral
ABCD
inscribed
in
a
circle
C
.
Show
that
the
opposite
angles,
in
the
quadrilateral
ABCD
,
are
angles
of
supplementary
mea-sures.
Hint
:
use
the
eight
angles
formed
by
the
intersection
of
the
two
diagonals
of
the
quadrilat-eral.
https://chingmath.fr
ABDOMC75o
chapExoCorrec/805
sacados/805
ABCOHC(d
chapExoCorrec/3928
sacados/3928
Asie
Juin 2009
ABDEC
chapExoCorrec/2938
sacados/2938
BDACC
CABCIJKM
304050ABCFigureno1ABCDE(DE==(ACFigureno2ABCEFigureno340o50o
Figure 1Figure 2ABCE60o20oABCDE(AC==(DE
Figure 3Figure 4ABC5;5cm4;5cm7;5cmBCDEest un losangede centreAABCDE
E.2939
In
the
plane,
consider
any
triangle
ABC
and
its
circumscribing
circle
C
;
the
point
M
is
any
point
on
the
circle
C
;
let
I
,
J
,
K
be
the
orthogonal
projects
of
the
point
M
onto
the
straight
lines
(
AC
)
,
(
BC
)
,
(
AB
)
,
respec-tively.
The
aim
of
this
exercise
is
to
show
that
the
points
I
,
J
,
K
are
aligned.
1
a
Establish
that
the
points
I
and
J
belong
to
the
circle
of
diameter
[
MC
]
.
b
Justify
that
the
angles
IJM
and
ICM
have
the
same
measure.
c
Deduce
the
relationship
:
ACM
=180
−
IJM
2
a
Justify
that
the
points
B
,
J
,
K
,
M
are
cocyclic;
Specify
the
nature
of
the
circle
to
which
they
belong.
b
Establish
the
equality:
ABM
=180
−
MJK
To
demonstrate
this
relationship,
we’ll
use
the
diago-nals
of
the
quadrilateral
JMBK
3
The
points
A
,
B
,
C
,
M
are
cocyclic
(as
in
question
2
b
)
;
we
accept
the
following
relationship
:
ABM
=
180
−
ACM
Deduce
that
the
points
I
,
J
,
K
are
aligned
The
straight
line
passing
through
these
three
points
is
called
Simson’s
straight
line.
6.
A
little
of
everything
E.2492
Demonstrate,
for
each
of
the
three
figures
below,
that
the
triangle
ABC
is
a
right-angled
triangle
using
the
information
provided.
E.3274
Complete
the
table
below
:
https://chingmath.fr
chapExoCorrec/2939
sacados/2939
CABCIJKM
chapExoCorrec/2492
sacados/2492
Groupe est - juin 2002 - 4 points
304050ABCFigureno1ABCDE(DE==(ACFigureno2ABCEFigureno340o50o
chapExoCorrec/3274
sacados/3274
Brevet juin 2010 - 6 points
Figure 1Figure 2ABCE60o20oABCDE(AC==(DE
Figure 3Figure 4ABC5;5cm4;5cm7;5cmBCDEest un losangede centreAABCDE
CCOPABQ6cm4cm
ABCOM5cm
Figure
1
Figure
2
Figure
3
Figure
4
Is
triangle
ABC
a
right
triangle
in
A
?
Yes
No
Yes
No
Yes
No
Yes
No
Number(s)
of
the
property
or
prop-erties
that
prove
this
List
of
properties:
1
If
a
quadrilateral
is
a
rhombus,
then
its
diagonals
have
the
same
midpoint
and
are
perpendicular.
2
If
two
lines
are
perpendicular
to
the
same
third
line,
then
they
are
parallel
to
each
other.
3
If,
in
a
triangle,
the
square
of
the
length
of
the
longest
side
is
not
equal
to
the
sum
of
the
squares
of
the
lengths
of
the
other
two
sides,
then
the
triangle
is
not
a
right
triangle.
4
In
a
triangle,
the
sum
of
the
measures
of
the
three
angles
is
equal
to
180
o
.
5
If
two
lines
are
parallel
and
a
third
line
is
perpendicular
to
one
of
them,
then
it
is
perpendicular
to
the
other.
6
If
a
quadrilateral
has
four
sides
of
equal
length,
then
it
is
a
rhombus.
7
If
two
angles
inscribed
in
a
circle
intercept
the
same
arc,
then
they
have
the
same
measure.
8
If
in
a
triangle,
the
square
of
the
length
of
the
longest
side
is
equal
to
the
sum
of
the
squares
of
the
lengths
of
the
other
sides,
then
this
triangle
is
a
right
triangle
and
the
right
angle
is
the
angle
opposite
the
longest
side.
7.
Unclassified
financial
years
E.5989
The
circle
C
has
center
O
and
radius
4
cm
.
Note
[
PQ
]
a
diameter
of
the
circle
C
.
We
construct
the
circle
C
of
center
P
and
radius
6
cm
.
Note
A
the
point
of
intersec-tion
of
the
circle
C
and
the
segment
[
PQ
]
and
B
one
of
the
of
the
intersection
points
of
the
two
circles
C
and
C
.
The
aim
of
the
exercise
is
to
determine
an
approximate
value
for
the
area
of
the
shaded
part.
We
will
work
with
rounded
measurements
:
1
a
Determine
the
area
of
the
triangle
BPQ
.
b
Deduce
the
area
of
triangle
POB
.
2
a
Determine
the
measure,
rounded
to
a
tenth
of
a
de-gree,
of
the
angle
PQB
.
b
Deduce
the
area,
rounded
to
the
tenth
of
cm
2
,
of
the
angular
sector
of
the
circle
C
defined
by
the
arc
PB
.
3
Deduce
a
measure,
rounded
to
the
tenth
of
cm
2
,
of
the
shaded
part.
E.6058
Consider
an
isosceles
triangle
ABC
at
A
such
that
angle
BAC
measures
50
o
and
AB
is
equal
to
5
cm
.
Let
O
be
the
center
of
the
cir-cle
circumscribed
around
trian-gle
ABC
.
The
line
(
OA
)
inter-sects
this
circle,
denoted
(
C
)
,
at
another
point
M
.
1
What
is
the
measure
of
an-gle
BAM
?
No
justification
is
required.
2
What
is
the
nature
of
triangle
BAM
?
Justify
your
answer.
3
Calculate
the
length
AM
and
round
it
to
the
nearest
tenth.
4
The
line
(
BO
)
intersects
the
circle
C
at
another
point
K
.
What
is
the
measure
of
angle
BKC
?
Justify
your
answer.
https://chingmath.fr
sacados/5989
CCOPABQ6cm4cm
sacados/6058
ABCOM5cm