(1-Cos b ) ( 1+ 1/ cosb) / (sen b / Cos b ) = sen b
(1-Cos b ) ( (cosb + 1) / cosb) / ( sen b / Cos b ) = sen b
(1- Cos b ) ( 1- Cos b) / sen b = sen b
Sen^2 b / sen b = sen b
Sen b = sen b
2) ctg b + sen b / 1 + Cos b = csc b
Cosb/ sen b + (sen b / 1+ Cos b ) = csc b
(Cos b + Cos^2 b+ sen ^2 b ) / [sen b * ( 1 + cosb)] = csc b
( Cos b + 1)/ [sen b * ( 1 + cosb)] = csc b
1/ sen b = csc b
Cscb = csc b
