1. Circle Proofs Allie Buksha 6-9-09 Geometry Mr. Chester

2. VOCABULARY RADIUS- a line segment drawn from the center point to a point on the circle RADIUS DIAMETER – a line segment from one point on the circle to another, and passes the center point DIAMETER SECANT – a line segment drawn from an external point to a point on the circle while passing through the circle once. SECANT TANGENT– a line segment drawn from an external point to a point on the circle, and it extended wont intersect the circle again TANGENT CHORD – a line from one point on the circle to another CHORD

3. TYPES OF ANGLES INSCRIBED ANGLES – an angle formed by two chords with the vertex on the circle INSCRIBED ANGLES CENTRAL ANGLES – an angle formed by two radii with the vertex on the circle CENTRAL ANGLES

4. THEOREOMS All radii of a circle are congruent In a circle, congruent central angles have congruent arcs In a circle, congruent arcs have congruent chords and vice versa A diameter perpendicular to a chord bisect the chord and its arcs Congruent chords in the same circle are equidistant from the center of the circle In a circle, if two chords are unequal, the shorter chord is farther from the center An angle inscribed in a semicircle is a right angle In a circle, inscribed angles that intercept the same arc are congruent Parallel lines intercept congruent arcs If a line is tangent to a circle then it is perpendicular to the radius at that point Two tangent segments drawn to a circle from an external point are congruent

5. BACK TO VOCABULARY

7. BACK TO THEOREOMS