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साबित करें कि `cos6x= 32 cos^(6) x- 48 cos^(4) x + 18 cos^(2) x -1 `

Answer» L.H.S. `cos6x= cos 2 (3x)`
`= 2 cos^(2) 3 x -1= 2 ( 4 cos^(3) x - 3 cos x^(2)) -1 `
`= 2[ 16 cos^(6) x - 24 cos^(4) x + 9 cos^(2) x ]-1`
`= 32 cos^(6) x - 48 cos^(4) x + 18 cos^(2) x - 1 = ` R.H.S.


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