[tex]sin3( \alpha ) = 3 \sin( \alpha ) - 4 { \sin^{3} ( \alpha ) }[/tex]
[tex]2( 3 \sin( \ \frac{\pi}{18} ) - 4 { \sin^{3} ( \ \frac{\pi}{18} ) })[/tex]
[tex]2(sin3( \ \frac{\pi}{18} ))[/tex]
[tex]2( \sin( \frac{\pi}{6} ) )[/tex]
[tex]2 \times \frac{1}{2 } = 1[/tex]
