Question

send me answer this sum

Answer 1

here,put the formula cos 2x=2cos^2 x -1..
and sin 2x= 2 sin x . cos x
so, cot^-1 ((1+cos x)/sin x)
=cot^-1 ((2cos^2 x/2)/2sinx/2 .cosx/2)
=cot^-1((cos x/2)/sin x/2)
=cot^-1 (cot x/2)
=x/2
is the answer