Circle+Geometry

//**Theorems as per Grade 11 CAPS document.**//


 * Getting to know the circle **


 * If a line is drawn from the centre of a circle perpendicular to a chord, then it bisects the chord. **


 * The perpendicular bisector of a chord passes through the centre of the circle. **


 * If an arc subtends an angle at the centre of a circle and at any point on the circumference, then the angle at the centre is twice the measure of the angle at the circumference. **


 * Angles in the same segment of a circle are equal. **


 * If a quadrilateral is cyclic, then the opposite angles are supplementary. **


 * If two tangents are drawn from the same point outside a circle, then they are equal in length. **


 * The angle between a tangent to a circle and a chord drawn from the point of contact is equal to an angle in the alternate segment. **


 * Summary **