Question

Determine sum=sinA+sin2A+sin3A...

Answer 1

Let
\ Multiply both sides by \[\sin \left( \frac{ A }{ 2} \right)\] \[S \times \sin \left( \frac{ A }{ 2 } \right)=sinA \times \sin \left( \frac{ A }{ 2 } \right) +........\] And apply \[\sin x siny=\frac{ 1}{ 2 }\left( \cos(x-y) +\cos(x+y)\right)\] And add all the terms.....

Answer 2

Can you close this post? Clears out the posts so we know who has been helped and who needs help.