Question

I have 2 questions

Answer 1

The number of solutions of :
sin2x-2cosx+4sinx=4 in [0,5pi] are?

Answer 2

If S=\[\tan^{-1} \frac{1}{n^2+n+1} + \tan^{-1} \frac{1}{n^2+3n+2}+\tan^{-1} \frac{1}{1+(n+19)(n+20)}\]
then tanS=?

Answer 3

in 2nd question, the 3rd term can be reduced to
\[\tan^{-1}(n+20) - \tan^{-1} (n+19)\]

Answer 4

@hartnn

Answer 5

@ganeshie8