Question
Question: If A + B + C = p and \(\sum_{}^{}{\cos A}\)cosec B cosec C = k, then k =...
If A + B + C = p and ∑cosAcosec B cosec C = k, then k =
A
2
B
3
C
2
D
3
Answer
2
Explanation
Solution
Sol. ∑cosAcosec B cosec C = k
Ž ∑∑sinA cos A = k sin B sin C sin A
∑∑sin2A = 2k sin A sin B sin C
Now in a D, ∑∑sin2A = 4 sin A sin B sin C
\ k = 2