1.

If `y=cot^(-1)(sqrt(cos"x"))-tan^(-1)(sqrt(cos"x")),`prove that `siny=tan^2x/2`

Answer» `y= cot^-1 sqrt(cos x) - tan^-1 sqrt cosx`
`y = cot^-1 sqrtcosx - tan^-1 sqrt cos x `
`= tan^-1 sqrt secx - tan^-1 sqrt cos x`
`y = tan^-1 ((sqrt secx - sqrt cos x)/(1+1)) `
`= tan^-1 ( (sqrt secx - sqrt cosx)/2)`
`y= tan^-1 ((1 -cosx)/(2 sqrtcosx))`
`tan y = (1- cosx)/(2 sqrt cosx)`
now, `sin y = (1 -cosx)/ (1+cosx) `
`= (2sin^2 (x/2))/(2 cos^2(x/2))= tan^2 (x/2)`
Answer


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