Circle

Forma of equations

Tangent

Radical axis

Geometry/applications

Normal

Family of circles

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Different cases of 2 circles

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Circle :

Intersection of circles

one inside another

Touching externally

Touching internally

Disjoint circles

Intersecting

Different forms of equations

Parametric form

x = r cos θ y = r sin θ

Circumscribing polygon

Triangle

L1L2 + $L2L3 + #L3L1 = 0

Quadrilateral

L1L2 + $L3L4 = 0

Two points on circle and chord subtending angle b/w them

Two points of diameter

(x-x1)(x-x2) + (y-y1)(y-y2) = 0

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Coordinate axes

circle

image

Radius and centre

Tangent

Chord of contact

Equation of pair of tangents

Normal to circle

Eq of tangent drawn to cirlce from external point

Director circle

Equation of tangent to circle having given slope

Geometrical properties

Position of point wrt circle

S1 >, =, < 0

Position of line wrt circle

D >, =, < 0

Equation of Chord of circle

T = S1

Length of tangent to circle

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Secant

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Max/Min dist b/w point and circle

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Family of Circles

Two points

Two intersecting circles

Fixed circle and line

Fixed point and a line

Radical Axis

Orthogonal intersection of circles

Of 3 cirlces

Of 2 circles

Cond for 2 degree homo eqn to represent circle

a=b

h =0

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Intercept of circle on axes

Eqn of circle passing through 3 points

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Equation of tangent to citcle on a point on circle