Analyzing Polar Equations for Conic Sections
Key Questions

There are two basic kinds of parabola(as it is convenient for me to say)
Type 1:
The parabola lying on, or parallel to the#x# axisThis parabola is of the form
#(yy_v)^2=4a(xx_v)# Where,
 focus is#(a+x_v,y_v)#
 directrix is the line#x=x_va#
 Vertex is#(x_v,y_v)# Type 2:
The parabola lying on, or parallel to the#y# axisThis parabola is of the form
#(xx_v)^2=4a(yy_v)# Where,
 focus is#(x_v,a+y_v)#
 directrix is the line#y=y_va#
 Vertex is#(x_v,y_v)# 
Answer:
The directrix is the vertical line
#x=(a^2)/c# .Explanation:
For a hyperbola
#(xh)^2/a^2(yk)^2/b^2=1# ,where
#a^2+b^2=c^2# ,the directrix is the line
#x=a^2/c# .