` Delta ABC` में सिद्ध कीजिए कि -
` (a+b+c)/(a+b+c) = cot. A/2 cot. C/2 `

Explanation

` R.H.S = cot. A/2 cot. C/2 `
` = sqrt((s(s-a))/((s-b)(s-c)))* sqrt((s(s-c))/ ((s-a)(s-b)))`
` = sqrt((s^(2))/(s-b)^(2))= s/(s-b)`
` = (2s)/( 2s-2b)= (a+b+c)/(a+b+c-2b)`
` = (a+b+c)/(a-b+c) = L.H.S`