Plus One Maths Notes Chapter 11 Conic Sections

Plus One Maths Notes Chapter 11 Conic Sections is part of Plus One Maths Notes. Here we have given Kerala Plus One Maths Notes Chapter 11 Conic Sections .

BoardSCERT, Kerala
Text BookNCERT Based
ClassPlus One
SubjectMaths Notes
ChapterChapter 11
Chapter NameConic Sections
CategoryPlus One Kerala

Kerala Plus One Maths Notes Chapter 11 Conic Sections

I. Circle
A circle is the set of all points in a plane that are equidistant from a fixed point in the plane. The fixed point is the centre and the fixed distance is the radius.
Equation of a circle with centre origin and radius r is x2 + y2 = r2.

Equation of a circle with centre (h, k) and radius r is (x – h)2 + (y – k)2 = r2.

General form of the equation of a circle is x2 + y2 + 2gx + 2fy + c = 0 with centre (-g, -f) and radius \(\sqrt{g^{2}+f^{2}-c}\).

II. Conic
A conic is the set of all points in a plane which moves so that the distance from a fixed point is in a constant ratio to its distance from a fixed-line. The fixed point is the focus and fixed line is directrix and the constant ratio is eccentricity, denoted by ‘e’.

III. Parabola (e = 1)

y2 = 4ax
Plus One Maths Notes Chapter 11 Conic Sections 1
Vertex: (0, 0)
Focus(S): (a, 0)
Length of Latusrectum: (LL’) = 4a
Equation of directrix (DD’) is x = -a

y2 = -4ax
Plus One Maths Notes Chapter 11 Conic Sections 2
Vertex: (0, 0)
Focus(S): (-a, 0)
Length of Latusrectum (LL’) = 4a
Equation of directrix (DD’) is x = a

x2 = 4ay
Plus One Maths Notes Chapter 11 Conic Sections 3
Vertex: (0, 0)
Focus(S): (0, a)
Length of Latusrectum (LL’) = 4a
Equation of directrix (DD’) is y = -a

x2 = -4ay
Plus One Maths Notes Chapter 11 Conic Sections 4
Vertex: (0, 0)
Focus(S): (0, -a)
Length of Latusrectum (LL’) = 4a
Equation of directrix (DD’) is y = a

IV. Ellipse (e < 1)

\(\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1\), a > b
Plus One Maths Notes Chapter 11 Conic Sections 5
1. Eccentricity, e = \(\frac{\sqrt{a^{2}-b^{2}}}{a}\)
(ae)2 = a2 – b2 ⇒ c2 = a2 – b2
2. b2 = a2(1 – e2)
3. Length of Latusrectum (LL’) = \(\frac{2 b^{2}}{a}\)
4. Focii, S(ae, 0) and S'(-ae, 0) or S(c, 0), S'(-c, 0)
5. Centre (0, 0)
6. Vertices A(a, 0) and A'(-a, 0)
7. Equation of directrix (DD’) is x = \(\frac{a}{e}\) and x = \(-\frac{a}{e}\)
8. Length of major axis (AA’) = 2a
9. Length of minor axis'(BB’) = 2b

\(\frac{x^{2}}{b^{2}}+\frac{y^{2}}{a^{2}}=1\), a > b
Plus One Maths Notes Chapter 11 Conic Sections 6
1. Eccentricity, e = \(\frac{\sqrt{a^{2}-b^{2}}}{a}\)
(ae)2 = a2 – b2 ⇒ c2 = a2 – b2
2. b2 = a2(1 – e2)
3. Length of Latus rectum (LL’) = \(\frac{2 b^{2}}{a}\)
4. Focii, S(0, ae) and S'(0, -ae) or S(0, c), S'(0, -c)
5. Centre (0, 0)
6. Vertices A(0, a) and A'(0, -a)
7. Equation of directrix (DD’) is y = \(\frac{a}{e}\) and y = \(-\frac{a}{e}\)
8. Length of major axis (AA’) = 2a
9. Length of minor axis (BB’) = 2b

V. Hyperbola (e > 1)

\(\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1\)
Plus One Maths Notes Chapter 11 Conic Sections 7
1. Eccentricity, e = \(\frac{\sqrt{a^{2}+b^{2}}}{a}\)
(ae)2 = a2 + b2 ⇒ c2 = a2 + b2
2. b2 = a2(e2 – 1)
3. Length of Latus rectum (LL’) = \(\frac{2 b^{2}}{a}\)
4. Focii, S(ae, 0) and S'(-ae, 0) or S(c, 0), S'(-c, 0)
5. Centre (0, 0)
6. Vertices A(a, 0) and A'(-a, 0)
7. Equation of directrix (DD’) is x = \(\frac{a}{e}\) and x = \(-\frac{a}{e}\)

\(\frac{y^{2}}{a^{2}}-\frac{x^{2}}{b^{2}}=1\)
Plus One Maths Notes Chapter 11 Conic Sections 8
1. Eccentricity, e = \(\frac{\sqrt{a^{2}+b^{2}}}{a}\)
(ae)2 = a2 + b2 ⇒ c2 = a2 + b2
2. b2 = a2(e2 – 1)
3. Length of Latus rectum (LL’) = \(\frac{2 b^{2}}{a}\)
4. Focii, S(0, ae) and S'(0, -ae) or S(0, c), S'(0, -c)
5. Centre (0, 0)
6. Vertices A(0, a) anti A'(0, -a)
7. Equation of directrix (DD’) is y = \(\frac{a}{e}\) and y = \(-\frac{a}{e}\)

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