Proof - Daisy
Proof: The tangent of a circle is perpendicular to its radius at the point of tangency.
| Statement | Reason |
| 1. O is center of circle | 1. Given |
| 2. AB and AC are tangents | 2. Given |
| 3. AO = AC | 3. Radii of circles are always congruent |
| 4. Angle OCB = Angle OAB | 4. This is the tangent-radius property |
| 5. OCB = OAB | 5. Hypotenuse Leg Postulate (share hypotenuse) |
| 6. AB = CB | 6. Corresponding Sides of Congruent Triangles |