If vertex of parabola is and equation of its directrix is , then the length of latus rectum is

Question

If vertex of parabola is  and equation of its directrix is , then the length of latus rectum is

Canvas Classes · Accepted Answer

🧠 Vertex and Directrix Given — One Formula Does It

Read the question. You are given the vertex of a parabola and the equation of its directrix. The latus rectum has length , where  is the distance from the vertex to the focus, and also equals the distance from the vertex to the directrix.

So the whole question reduces to: find the perpendicular distance from the vertex  to the line . That gives . Multiply by 4. Done.

This is a one-step problem if you remember that  = distance(vertex, directr

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