E  (D  E(3; 7; 6). A IZ12 Z22 4 I A2 2 I    A 1 1 I   ...

2) E  (d

2

)  E(3; 7; 6).

a i

z

12

z

22

4 i a

2

2 i    a 1 1 i

         .

Câu VII.a:

Câu VI.b: 1) (C): x

2

y

2

 6 x  2 y   5 0  Tâm I(3; 1), bán kính R = 5 .

d I

( , ) 5

 

 

cos( , ) 2

a b c

   

d

 

a 2, b 1, c 10