Pre-Cal 40S Slides May 13, 2008

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The Whisper Room

What does this have to do with ellipses?

b

ca

F1F2b

A1A 2

B1

B2

Oa

c

The Anatomy of The EllipseP

O is the centre.A A is the length of the major axis. It's length is 2a.

21 B B is the length of the minor axis. It's length is 2b.

21

OA = OA is the length of the semimajor axis with length a.

1 2

OB = OB is the length of the semiminor axis with length b.

1 2

A & A are called the vertices of the ellipse.

21

B & B are called the endpoints of the minor axis.

21

PF & PF are the focal radii of the ellipse.

21 F & F are called the foci. They are c units from the centre.

21

b

ca

F1F

2b

A1

A2

B1

B2

Oa

c

VERTICAL

ELLIPSE

Horizontal Ellipse Vertical Ellipse

ab

ca F1F2b

A1A 2

B1

B

The Pythagorean Property

b2 c2 a2+ =

b2c2 a2-=

Vertical EllipseHorizontal Ellipse

Constant

BY SYMMETRY

FOCAL RADII PROPERTY

Sketch each ellipse. Identify the length of the major and minor axes, the coordinates of the center, foci and vertices.

Sketch each ellipse. Identify the length of the major and minor axes, the coordinates of the center, foci and vertices.

From Standard to General Form and Back Again ...

Standard Form

General Form

Standard Form

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