Question

Y=√{(1-cosx)/(1+cosx)}, then dy/dx=?

Answer 1

y =√(1-cosx)/(1+cosx)
y = √(1-cosx)(1-cosx)/(1+cosx)(1-cosx)
y = 1-cosx /sinx = cosecx - cotx

dy/dx = d cosecx/dx - dcotx/dx
= -cosecxcotx + cosec²x

Thats it!
I hope you understand the solution.
All the best!