Given: Equation of the curve  ……….(i)

  ……….(ii)

(i) If tangent is parallel to axis, then Slope of tangent = 0

   = 0

  From eq. (i), 

Therefore, the points on curve (i) where tangents are parallel to axis are .

(ii) If the tangent parallel to axis.

 Slope of the tangent = 

  From eq. (ii),  

  From eq. (i),  

Therefore, the points on curve (i) where tangents are parallel to axis are .