

M //</N < 



123. Normal to the conic la* 4 

 at a given point. The normal to a curve baa been de- 

 fiiif- 81) aa a atraight line perpendicular to a tan- 



, and jMtftsing through the point of contact. Therefore, 

 i the equation of a n-nn.il to a conic, at a ^ 

 tin- .-..I. .iilv neooauary to write the cqui 



he tangent to the conir at that point (by Ar .md 



thru timl the equation ..; a perpeinli-uUr to th,- tangent 

 h paaaea through the |K>int of conta* \rtn. 53, 



\AMPLR. To fin.l tin equation of the normal to the 



ellipse 



18 



point (8, 2). 



u of ti,- tangent 



at the ]M.ini (3, 2) 18 



4-3y= 11 



JM ij ir lint* through ( '-\, 2) ia 



, therefore, the required normal. 



timl tii.- normal to the 



le point /', on tin- .-urve. 



angent at /' 



whose equa: 



-Oi . . . (1) 

 The equation of tlu- 







