Circle thereoms

Circle thereoms

1. Thereom 1

   • The lengths of two tangents from a point to a circle are equal.

2. Thereom 2

   • The perpendicular from the centre of a circle to a chord bisects the chord.

3. Thereom 3

   • The angle subtended at the centre of a circle is twice the angle at the circumfrence.

4. Thereom 4

   • The angle in a semicircle is a right angle.

5. Thereom 5

   • Angles in the same segment are equal.

6. Thereom 6

   • Opposite angles of a cyclic quadrilateral are supplementary (add up to 180 degrees).

7. Thereom 7

   • The angle between a tangent and a chord is equal to the angle in the alternate segment,