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प्रश्न
If A, B and C are the angles of a ΔABC, prove that tan `((C + "A")/2) = cot B/2`
उत्तर
In ΔABC
A + B + c = 180°
⇒ A + C = 180° - B ..........(i)
Now,
LHS `= tan (("C"+"A")/2)`
`=tan ((180^circ - "B")/2)` [Using (i)]
`= tan (90^circ - "B"/2)`
`= cot "B"/2 `
= RHS
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