s i n e   - ^ 2 
 
 c o s i n e   s q r t ( 1 - ( - ^ 2 ) ^ 2 ) 
 
 
 
 t a n g e n t   ( - ^ 2 ) / s q r t ( 1 - ( - ^ 2 ) ^ 2 ) 
 
 
 
 x = k - k ^ 2 
 
 