Parabola focus at and directrix is
Since the directrix is , then the parabola is horizontal.
Standard form of horizontal parabola is .
Where is vertex.
If then the parabola opens to the left and
parabola opens to the right.
Directrix is and focus at
.
Focus =
.
Directrix
.
.
Substitute in
.
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Vertex of parabola is .
Find the value of .
Substitute in
.
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Substitute and
in standard form.
.
The parabola equation is .
Latus rectum is the line segment of a parabola perpendicular to axis which has both ends on the curve.
\Obtain the points define the latus rectum, let
Then
The two points that define latus rectum are
Graph:
\Draw the coordinate plane.
\Plot the vertex, focus, and the two points
Draw the directrix line.
\Connect the plotted points with smooth curve.
\The parabola equation is .
The two points that define latus rectum are
Graph of :
.