Question

1- costheta÷sintheta+sintheta÷1-costheta​

Answer 1

let theta be x,then
1-cos x = 1- 1+2sin²x/2
= 2sin²x/2
so, (2sin²x/2) /sinx ÷ sinx /(2sin²x/2)
=( 4sin⁴x/2 + sin²x )/2sin²x/2 sinx