Ellipse 4Given the two foci (F1 and F2) and a line of tangency, construct the ellipse and the point of tangency.  The foci must fall on the same side of the line of tangency. Here, focus F2 is reflected across the tangent line to image F2ʹ. Line F1F2ʹ intersects the tangent line at point T, the point of tangency.  Left now with the foci and a point on curve (T), the construction can be completed using Ellipse 3 as a guide. In the interactive sketch below drag the given objects to confirm that the solution holds up. |