Circle Theorems

Circle Theorems

1. Tangent + Radius meet at 90 degrees

2. Two radii form an isosceles triangle

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

4. The angle at the centre of a circle is twice the angle at the circumference

5. The angle in a semi-circle is 90 degrees

6. Angles in the same segment are equal

7. Opposite angles in a cyclic quadrilateral are equal.

8. Tangents from the same point are the same length

9. Alternate segment- angle between a tangent and chord is equal to the in the opposite segment.

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