Points of Intersection Between a Line and a Conic

Concept sheet | Mathematics

To find the intersection point(s) between a line and a conic, we solve the system of equations composed of first-degree and second-degree equations.

Rule
  1. Use the substitution method to obtain an equation with one variable.

  2. Manipulate the equation so it equals |0.|

  3. Solve the equation to find the value(s) of the isolated variable.

  4. Replace the value(s) obtained into one of the original equations to obtain the value(s) of the other variable.

  5. Write the coordinates of the point(s) of intersection.

Important!

Unlike the intersection between a parabola and a conic, there are three possible cases regarding the number of solutions:

  • the line and the conic do not intersect;

  • the line and the conic intersect only at one place, called the point of tangency;

  • the line and the conic intersect at two distinct places.

In the following interactive video, select a conic and drag the cursor to study the possible cases.

The Intersection Points Between a Line and a Circle

Example

Determine the coordinates of the point(s) of intersection between the line |y=2x+5| and the circle |x^2+y^2=10.|

See solution

The Intersection Points Between a Line and an Ellipse

Example

Determine the coordinates of the point(s) of intersection between the line |y =-2x+6| and the ellipse |\dfrac{x^2}{36}+\dfrac{y^2}{49}=1.|

See solution

The Intersection Points Between a Line and a Hyperbola

Example

Determine the coordinates of the point(s) of intersection between the line |y=2x-13| and the hyperbola |\dfrac{x^2}{25}-\dfrac{y^2}{100}=1.|

See solution

The Intersection Points Between a Line and a Parabola

Example

Determine the coordinates of the point(s) of intersection between the line |y=4x-7| and the parabola |(x-4)^2=3(y+6).| 

See solution