BÀI 5 TÍCH( ( ) ) ( ( ) )

3) CMR

a b

b c

c a

+

0

2cos 10

2

1

tg

a tg

a

a

a

+

b

+

c

+

d

=

+

+

+

sin

sin

sin

sin

4sin

.sin

.sin

( ) ( ) ( )

+

− =

0

0

35

25

2

2

2

( )

+

+

a