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If A=30, then show that sin3A=3sinA...

If A=30, then show that `sin3A=3sinA-4sin^(3)A`

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L.H.S. `=sin 3A=sin(3xx30^(@))=sin 90^(@)=1`
R.H.S` =3sinA -4sin ^(3)A=3 sin30^(@)-4sin^(3)30^(@)`
`=3((1)/(2))-4((1)/(2))^(3)=(3)/(2)-(4)/(8)=(3)/(2)-(1)/(2)=(2)/(2)=1`
`:.` L.H.S.=R.H.S
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