1.

If `x_(1)` and `x_(2)` are two distind roots of the equation `a cos x+b sinx=c`, then `tan"" (x_(1)+x_(2))/(2)` is equal toA. `(a)/(b)`B. `(b)/(a)`C. `(c)/(a)`D. `(a)/(c)`

Answer» Correct Answer - B
`a cos x+b sin x=c`
`rArr (a(1-tan^(2)(x)/(x)))/(1+tan^(2)(x)/(2))+(2btan((x)/(2)))/(1+tan^(2)((x)/(2)))=c`
`rArr(c+a)tan^(2)((x)/(2))-2btan((x)/(2))+c-a=0`
`rARr tan((x_(1))/(2))+tan ((x^(2))/(2))=(2b)/(c+a)`
and `tan((x_(1))/(2))tan((x_(2))/(2))=(c-a)/(c+a)`
`rArr tan((x_(1)+x_(2))/(2))=((2b)/(c+a))/(1-(c-a)/(c+a))=(2b)/(2a)=(b)/(a)`


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