14.1 Introduction 14.2 Standard Form/General Form/Center Radius Form of the Equation of a Circle 14.3 Finding the Centre and Radius of a Circle 14.4 Position of a Point with Respect to a Given Circle 14.5 Condition for a Line to be a Tangent 14.5.1 Condition for a Line to Touch the Circle with Centre O(0, 0) 14.5.2 Condition for a Line to Be Tangent to the Circle with Centre C(g, f ) 14.6 Diameter Form of the Equation of a Circle 14.7 Tangents 14.7.1 Equations of Tangents to the Circle of the Form x2 + y2 = a2 14.7.2 Equations of Tangents to the Circle of the Form x2 + 2gx + y2 + 2fy + c = 0 14.8 Points of Intersection of a Circle and a Straight Line 14.9 To Find the Length of the Tangent from P(x1, y1) to the Circle 14.10 Condition for Two Circles to Touch Each Other 14.11 Normal 14.12 Equations of the Circles in Some Special Cases 14.12.1 The Equation of a Circle of Radius r, Passing Through the Origin and Having Its Center on the (i) x-axis and (ii) y-axis 14.12.2 Equation of a Circle of Radius r and Touching Both the Axes 14.12.3 Equation of a Circle on the Join of A (x1, y1) and B (x2, y2) as a Diameter 14.12.4 Equation of a Circle Passing Through the Origin and Making Intercepts a and b on the Axis 14.13 Angle of Intersection of Two Circles 14.13.1 Orthogonal Circles 14.14 Equation of the Common Chord (Radical Axis) of the Two Circles 14.15 Family of Circles Exercise