1.

If `tanalpha`is equal to the integral solution of the inequality `4x^2-16 x+15

Answer» Correct Answer - D
We have `4x^(2)-16x+15lt0`
`rArr (3)/(2)ltxlt(5)/(2)`
Therefore, the integral solution of
`4x^(2)-16x+15lt0` is `x=2`.
Thus, `tan alpha=2`. It is given that `cos beta=tan45^(@)=1`.
`therefore sin(alpha+beta)sin(alpha-beta)=sin^(2)alpha-sin^(2)beta`.
`(1)/(1+cot^(2)alpha)(1-cos^(2)beta)`
`=(1)/(1+(1)/(4))-0=(4)/(5)`


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