The value of `sin^2 12^0+sin^2 21^0+sin^2 39^0+sin^2 48^0-sin^2 9^0-sin^2 18^0` is _______

Explanation

`L.H.S.=(sin^2 5^@+sin^2 85^@)+(sin^2 10^@+sin^2 80^@)+...`
`+(sin^2 40^@+sin^2 50^@)+(sin^2 45^@+sin^2 90^@)`
`(sin^2 5^@+sin^2 5^@)+(sin^2 10^@+sin^2 10^@)+...`
`+(sin^2 40^@+sin^2 40^@)+(sin^2 45^@+sin^2 45^@)`
`=(1+1+1+1+1+1+1+1)`
`+(1/sqrt2)^(2)+1=9 1/2=R.H.S.`