$\"\"$

\

Observe the diagram :

\

The focal zone is located at the focus of the parabolic mirror.

\

The depth of the parabolic mirror is $\"\"$ .

\

Width of the parabola is $\"\"$ .

\

Since Width of the parabola is $\"\"$ , $\"\"$ width of the reflector will exist on above $\"\"$ -axis

\

and $\"\"$ width of the reflector will exist on below $\"\"$ -axis.

\

The point lie on the parabolic mirror are $\"\"$ and $\"\"$ .

\

The vertex of a parabola in standard form is $\"\"$ .

\

Since the vertex is located at origin, vertex is $\"\"$ .

\

The equation of parabola is $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ in above equation.

\

$\"\"$

\

The focus of a parabola in standard form is $\"\"$ .

\

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

\

$\"\"$

\

The focus of a parabola is $\"\"$ .

\

Thus, the distance between parabola to focal zone is $\"\"$ .

\

$\"\"$

\

The distance between parabola to focal zone is $\"\"$ .