1 1 7( KHỐI A_2008 ) + =  − 4 SINX   ΠX XSIN 43SIN 2 −  −...

6. 1 1 7

( Khối A_2008 )

+ =  − 

4 sin

x

   

π

x x

sin 4

3

sin 2

 − 

 

− −

ðS: ^{, , 5 ,} ( )

π π π

= + = + = + ∈Z

x π k x π k x π k k

4 8 8

1 2 sin cos

− =