Question 6  Ellipses & Parabolas
Key Concepts
How to Draw an Ellipse  Circle Method
1  Draw a circle with a diameter equal to the major axis and a circle with a diameter equal to the minor axis using the same centre
2  Divide the circles into 12 slices using your 30 deg set square 3  Draw a vertical line down from each point where the lines meet the outer circle and draw a horizontal line across where the lines meet the smaller circle. Mark out the points where the horizontal and vertical lines meet. 4  Use these points to freehand sketch the ellipse


How to Draw a Tangent to an Ellipse at a Point, p1  Locate the 2 focal points, F1 & F2
2  Draw a line from each focal point to P and extend them outside the ellipse 3  Bisect the angle between the focal point lines as shown in blue
4  The tangent is the line that bisects the angle at P

Finding the minor axis given a point on the ellipse 
Parabola
How to Draw a Parabola (Rectangle Method)


Past Exam Questions
Simpler ellipse questions also appear in Section A
Useful Tips
Useful Tips
 Know how to find the minor axis given the major axis and a point on the ellipse (p244 in the Textbook)
 You can use axial symmetry to draw the second half of an ellipse or parabola
 If you can't figure out how to find a certain point, guess it and keep going with the rest of the construction. You'll only be penalised once.