5102 - 5102
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1st exercise : (4 pts)
In the following table, just one of the proposed answers is correct. Indicate the number of the question
and its corresponding answer and justify.
No
Answers
Questions
1
, then
12
3 n
4
9
43
9
1
1
1
, b  25 and c  5 and if x 
,
10
b a  c   1
2
2
25
2 5
2 5  1
65
28
13
8
Isosceles
Right isosceles
equilateral
If a is a real number such that : a  4.694 
1.
a-1 = 
If
2.
then x = ...
If C 
3.
Let
252
45 5
 , then C  
112
245 4
ABC
be
triangle
such
4 3 5
15  3
5
3
, AB 
,
and AC 
3
3
3 3
then the triangle ABC is 
4.
BC =
that:
2nd exercise: (4 pts)
Let ABCD be a quadrilateral such that: (The unit of length is the cm).
2
10
3
64
61  5 
1 1 1
AB  2.25 
; BC  12.25  
; CD  7.3     and AD      2  12 .
21 2
9
12  3 
2 3 4
1) a) Reduce, then say if each of the given numbers is either rational or irrational, and justify your
answer. (2 pts)
b) Deduce the nature of ABCD. ( pt)
2) Let E be the foot of the height issued from A to [DC].
h is the length of [AE] (AE = h), such that :
2 4 
2 1 
2 2 .
a) Show that h is an integer. (1 pt)
b) Calculate the area of the quadrilateral ABCD. ( pt)
2/1
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3rd exercise : (6 pts)
Consider the following algebraic expressions:
E  x    m  1 x 3  3x 2   m  3 x   2m  1 ,
G  x    4x 2  4x  1   6x  3 x  2   5  20x 2 , and
F  x   (a  x ) 2   x 2  1 b  2x   a  x 3  a   c  x  1  1 .
(a, b, c and m are four real numbers and m is a parameter)
1) Calculate m so that 1 a root of E (x) . (1 pt)
For the rest of the exercise, consider : E  x   2x 3  3x 2  4x  5 .
2) Show that E
 2  is an integer. (1pt)
3) a) Show that : F  x    a  2  x 3  1  b  x 2   2a  2  c  x  b  c  1. (1pts)
b) Calculate a, b and c so E (x) and F (x) are identical. (1pt)
4) Factorize G(x) then deduce its roots. (1 pts)
4th exercise: (10 pts)
In the following figure we have:
* (C) is a circle of center O, of radius R and of diameter [AB].
2
* C is a point on [AO] such that: AC  R .
3
* (d) is the perpendicular to (AB) at B.
* D is a point on (d) such that: DO B  60 .
o
1) Reproduce the figure. ( pt)
4
2) a) Show that : BC = R . ( pt)
3
b) Determine the nature of the triangle DOB,
and then calculate DB in terms of R. ( pt)
c) Calculate, in terms of R, the area of the triangle COD. ( pt)
3) Let M be the orthogonal projection of B on [CD]. The perpendicular bisector of [AB] cuts [CM] at N.
Show that M, N, O and B belong to the same circle of center I and of diameter to be precised. ( pt)
4) The tangent to (C) issued from D other than (d), touches the circle at E, (E is the point of tangency),
and it cuts the line (AB) at P.
 B ? Justify. ( pt)
a) What does [DO) represent for the angle ED
b) Using the triangle BDP, show that: DP = 2  BD. ( pt)
c) Deduce that E is the midpoint of [DP]. ( pt)
5) F is the symmetric of E with respect to (AB).
a) Show that AEOF is a rhombus. ( pt)
b) Deduce that the points F, O and D are collinear. ( pt)
c) Show that (PF) is tangent to (C) at F. ( pt)
6) In this part, we suppose that D varies on the straight line (d).
a) Indicate the fixed points among O, M, N, D and B. ( pt)
b) What is the locus of I, the midpoint of [BN]? Justify. ( pt)
c) Let K be the intersection point of [DO] and [EB].
On which line does K vary? Justify. ( pt)
2/2
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