... vuụng nh A nờn:
2 2
2
2 2 2 2 2
1 1 1 a b
BK
BK AB BC a b
= + =
+
.
+ SAB cõn nh S, BH l ng cao nờn
2
2
a
c .a
SI.AB
4
HB
SA c
= =
+ Do HBK vuụng ti K nờn:
2 2 2 2 2
2 2 2
2 2 2
(4c a )a a ... t )
2
−
+ a.
2
t 1
2
−
= 0 ⇔ t
3
– at
2
– 3t + a = 0 (2) .
Câu a /
(1 đ) + Với a =
2
: (2) trở thành:
t
3
–
2
t
2
– 3t +
2
= 0 ⇔ (t +
2
)(t
2
- 2
2
t...
... - m)
2
+ (y - R)
2
= R
2
hay
(C): x
2
+ y
2
– 2mx – 2Ry + m
2
= 0.
• Phương trình đường tròn đường kính AI là:
(C’): (x – m /2)
2
+ (y – R /2)
2
=
2 2
m + R
4
hay
(C’): x
2
+ y
2
– ... mx + Ry – m
2
= 0 ⇔ (d): y = f(x) = -
2
m m
x
R R
+
.
• Xét hàm số y = g(x) =
2
1
x
4R
−
.
• Hệ
2
2
2
m m 1
x x
f (x) g(x)
(x 2m) 0
R R 4R
x 2m
f '(x) g '(x)
m x x 2m...
... the correct statements or answer the questions below (0 ,25 pt
each)
1.Stress is more common in this century than in previous century √
2. Stress can cause illness and illness can cause stress
3.Some ... wonderful invention
C. The uses of nylon in our everyday life
D. The role of nylon in industry
2. The word strong in the passage is closest in meaning to:
A. Powerful B. Best C. Solid D. D...