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Chapter 18 of 42
Revision Notes

CircleRevision Notes

JEE Mains · Mathematics

Quick revision notes for Circle — key concepts, formulas, and definitions for JEE Mains Mathematics preparation.

Revision Notes — Circle

Key concepts, formulas, and definitions from Circle for JEE Mains Mathematics preparation.

Key Topics to Revise

1

Definition and Basic Equation of Circle

  • A circle is the locus of points equidistant from a fixed point (center)
  • Standard form: (x-h)² + (y-k)² = r² where (h,k) is center and r is radius
  • General form: x² + y² + 2gx + 2fy + c = 0
2

Circle Passing Through Three Points

  • Three non-collinear points uniquely determine a circle
  • Use general form x² + y² + 2gx + 2fy + c = 0
  • Substitute three points to get three equations in g, f, c
3

Parametric Form of Circle

  • For circle x² + y² = a²: x = a cos θ, y = a sin θ
  • For circle (x-h)² + (y-k)² = r²: x = h + r cos θ, y = k + r sin θ
  • Parameter θ is the angle from positive x-axis
4

Tangent to Circle

  • Tangent at point (x₁,y₁) on circle S = 0 is given by T = 0
  • For circle x² + y² = a²: tangent at (x₁,y₁) is xx₁ + yy₁ = a²
  • Tangent with slope m to x² + y² = a²: y = mx ± a√(1+m²)

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Key Concepts

A circle is the locusGeneral equationCircle through three pointsTangent at point (x₁Chord equation bisected at (x₁

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Frequently Asked Questions

What topics are covered in Circle for JEE Mains?

Circle is an important chapter in JEE Mains Mathematics. It covers key concepts and formulas that are frequently tested in the exam. Key topics include: Definition and Basic Equation of Circle, Circle Passing Through Three Points, Parametric Form of Circle, Tangent to Circle.

Circle is a frequently tested chapter in JEE Mains Mathematics. Questions from this chapter appear regularly in previous year papers. There are 75 practice questions available for this chapter.

Start by understanding the core concepts, then solve practice questions. Focus on formulas and their applications. Use revision notes for quick review before the exam.