SME
Grade 12 Math
Polar equations of conics and rotation of axes
The main lesson, then each kind of problem it solves.
Polar equations of conics and rotation of axes
Main lesson
Polar conics with sin θ
Use this for “Name the conic r = 4 ÷ (1 + sin θ), its eccentricity and its directrix.”
A polar ellipse: vertices and axes
Use this for “For r = 3 ÷ (1 − 0.5 cos θ), find the vertices, the center and the lengths of the axes.”
A polar parabola
Use this for “Find the vertex and the directrix of r = 4 ÷ (1 − cos θ), and the point at θ = 90°.”
Rotating the axes
Use this for “Through what angle should the axes turn to remove the xy term of 4x² + 2xy + 2y² = 1? Which conic is it?”
The equation after turning the axes
Use this for “Turn the axes to remove the xy term of 4x² + 2xy + 2y² = 1 and write the equation in x′ and y′.”