Gr 11 (Euclidean Geometry)

1.   Revision of all geometry rules from grade 7 to 10. 2.        Tangent to a circle is perpendicular to the radius.

3.   Then investigate and prove the theorems of the geometry of circles:

**The line drawn from the centre of a circle perpendicular to a chord bisects the chord.

**The line drawn from the centre of a circle to the midpoint of a chord is perpendicular to the chord.

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

**The angle at the centre of a circle is double the size of the angle at the circumference of the circle

Angles subtended by a chord of the circle, on the same side of the chord, are equal.

**The opposite angles of a cyclic quadrilateral are supplementary.

Two tangents drawn to a circle from the same point outside the circle are equal in length.

**The angle between the tangent to a circle and the chord equal to the angle in the alternate segment.

The proof of the Theorems marked with ** are examinable.

4. Use the above theorems and their converses, where they exist, to solve riders.