Conic Sections — Class 11 CBSE Mathematics revision notes
A 4-page visual revision sheet for Conic Sections, written for Class 11 CBSE Mathematics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDFA preview of page 1 — all 4 pages open full size in the app.
Conic Sections in one look
circle, parabola, ellipse, hyperbola, one number apart
Conic sections, and where they come from
each curve is points P obeying one distance rule: a fixed focus, a fixed directrix
eccentricity e=PF/PM, focus distance over directrix distance, is the SINGLE deciding number
e=0: circle. 0<e<1: ellipse. e=1: parabola. e>1: hyperbola, and these four ranges never overlap
Eccentricity: the limiting cases
e=0 — circle, foci merge at the centre
0<e<1 — ellipse, bounded closed curve
e=1 — parabola, one focus, one directrix, one branch
e>1 — hyperbola, two unbounded branches
Circle: centre-radius and general form
centre (h,k), radius r(x-h)^2+(y-k)^2=r^2
general form, centre and radius drop out of g,f,cx^2+y^2+2gx+2fy+c=0
centre(-g,-f)
radius, real only when g^2+f^2-c>0r=√g^2+f^2-c
Worked: centre and radius from the general equation
Q. find the centre and radius of the circle x^2+y^2-4x+6y-3=0
match against x^2+y^2+2gx+2fy+c=0: 2g=-4 so g=-2, 2f=6 so f=3, c=-3
centre = (-g,-f)=(2,-3)
radius: r=√g^2+f^2-c=√(-2)^2+3^2-(-3)
=√4+9+3=√16=4
Answer: centre (2,-3), radius 4
Page 1 of 4. The full sheet, all 4 pages, opens free in the app.
What this Conic Sections sheet covers
Conic sections, and where they come from
Eccentricity: the limiting cases
Circle: centre-radius and general form
centre (h,k), radius r
general form, centre and radius drop out of g,f,c
centre
radius, real only when g^2+f^2-c>0
Worked: centre and radius from the general equation
These notes are not a standalone PDF. CapCompass plans Mathematics chapter by chapter against your real exam dates and free hours, and when the plan reaches Conic Sections the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.