Parabola 2Given the axis, the focus (F), and one tangent line, construct the parabola and the point of tangency.  Reflect the focus, F, across the tangent line, to image point Fʹ, which falls on the directrix. Construct the directrix through Fʹ, perpendicular to the axis. Let the axis and directrix intersect at A. Construct the axial vertex, V, midpoint of FA. Through Fʹ construct a diameter parallel to the axis, and let it meet the line of tangency at B, the point of tangency.  Now the parabola construction is completed from the focus and directrix. Drag the given objects on the image below to confirm the construction. |