Question 1023508
 {{{csc^2(B) (1 + 2cosB +cos^2(B)) = csc^2(B)(1+cosB)^2 = (cscB + cscB*cosB)^2}}}

={{{(cscB + cotB)^2 = (cscB + cotB)^2 /(csc^2(B) - cot^2(B)) = (cscB+cotB)/(cotB - cotB)}}}.

We used the identity {{{csc^2(B) - cot^2(B) = 1}}}