sin^2 x + 4 sinx +3 3 + sinx
-------------------------- = -------------------
cos^2 x 1 - sinx
factor the numerator
(sinx +3) (sinx+1) 3 + sinx
-------------------------- = -------------------
cos^2 x 1 - sinx
cos^2 = 1-sin^2x
(sinx +3) (sinx+1) 3 + sinx
-------------------------- = -------------------
1- sin^2x 1 - sinx
factor the denominator
(sinx +3) (sinx+1) 3 + sinx
-------------------------- = -------------------
(1-sinx ) (1+sinx) 1 - sinx
cancel the common term (1+sinx) and (sinx +1)
(sinx +3) 3 + sinx
-------------------------- = -------------------
(1-sinx ) 1 - sinx
reorder the first term
3+sinx 3 + sinx
-------------------------- = -------------------
(1-sinx ) 1 - sinx