Question

Sin.Sinπ/18+ sin.sinπ/9+ sin.sin7π/18+sin.sin4π/9=2

Answer 1

Answer:

1/8

Step-by-step explanation:

1/8

k=sinπ/8sin5π/18sin5π/18sin7π/18

=sin10

∘

sin

50

∘

sin

70

∘

=

2

1

​

[cos40

∘

−cos60

∘

]sin70

∘

=

2

1

​

cos40

∘

sin70

∘

−

4

1

​

sin70

∘

=

4

1

​

[sin110

∘

+sin30

∘

]−

4

1

​

sin70

∘

=

4

1

​

sin(180

∘

−70

∘

)+

4

1

​

×

2

1

​

−

4

1

​

sin70

∘

=

8

1