cos A csc B csc C + cos B csc A csc C + cos C csc A csc B
If A + B + C = π , find the value of above expression.
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That was really fast!
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Lol ... Thanks... Now its already six months since I've started writing in latex :-D
Or we could have used conditional trigonometric identities that if A+B+C =Pi
then sin2A+Sin2B+sin2C = 4sinAsinBsinC
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Yep... There could be so many ways to reach the final answer... :-)
Why only 3 π any A and B , A + B < π and C= π - A - B will be OK.
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Let the given expression be G . I'll be using I . cos ( A + B ) = − cos C ( By taking cos of A + B = π − C ) I I . tan A + tan B + tan C = tan A tan B tan C ( By taking tan of A + B + C = π ) I I I . csc y = sin y 1 and I I I I . cos ( x + y ) = cos x cos y − sin x sin y .
G = − cyc ∑ ( sin B sin C cos ( B + C ) ) = cyc ∑ ( 1 − cot B cot C ) = 3 − 1 cyc ∑ ( tan A tan B tan C tan A )
∴ G = 2
PS: Don't write in comments: just assume A = B = C = 3 π and you are done XD