In `Delta ABC, "cot"(A)/(2) + "cot" (B)/(2) + "cot" (C)/(2)` is equal to

Question

In `Delta ABC, "cot"(A)/(2) + "cot" (B)/(2) + "cot" (C)/(2)` is equal to

In `Delta ABC, "cot"(A)/(2) + "cot" (B)/(2) + "cot" (C)/(2)` is equal to
A. `(Delta)/(r^(2))`
B. `((a + b + c)^(2))/(abc) 2R`
C. `(Delta )/(r)`
D. `(Delta)/(Rr)`

Monjur Alahi

5 views

2025-01-04 04:42

1 Answers

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Salim Ahmed Kawsar · Accepted Answer · 2023-02-05T15:29:48+06:00

Salim Ahmed Kawsar

Correct Answer - A
`cot.(A)/(2) + cot.(B)/(2) + cot.(C)/(2)`
`= (s(s-a))/(Delta) + (s(s-b))/(Delta) + (s-(s -c))/(Delta)`
`= (s)/(Delta) [3s - (a + b + c)] = (s^(2))/(Delta) = ((Delta//r)^(2))/(Delta) = (Delta)/(r^(2))`

5 views Answered 2023-02-05 15:29