### Tangent-Radius Theorem-w

If a line is tangent to a cirlce, then it is perpendicular to the radius drawn to the point of tangency

### Converse Tangent-Radius Theorem-w

If a line is perpendicular to the radius, then the line is tangent to the circle

### External Point-Tangent Theorem-w

If two segments are tangent to a circle from the same external point, then the segments are congruent.

### Arc Addition Postulate

The measure of an arc formed by two adjacent arcs is the sum of the measures of the two arcs

### Central Angle, Chords, and Arcs Theorem-w

In a circle or congruent cirlces:

1. Congreunt central angles have congruent chords

2. Congruent chords have congruent arcs

3. Congruent arcs have congruen central angles.

### Perpendicular Radius Theroem-w

In a cirlce, if a radius (or diameter) is perpendicular to a chord, then it bsects the chrd and its arc

### Perpendicular Chord Bisector-w

In a circle, the perpendicular bisector of a chord is a radius (or diameter).

### Inscribed Angle Theorem

The measure of an inscribed angle is half the measure of its intercepted arc.

### Inscribed Angle Corrolary-w

If inscribed angles of a circle intercept the same arc or are subtended by the same chord or arc, then the angles are congruent.

### Inscribed Angle Subtending Theorem-w

an inscribed angle subtends a semicircle if and only if the angle is a right angle.

### Inscribed Quadrilateral Theorem-w

If a quadrilateral is inscribed in a circle, then its opposite angles are supplementary

### Tangent/Secant Intersection Theorem-w

If a tangent and a secant (or a chord) intersect on a circle at the point of tangency, then the measure of the angle formed is half the measur off the intercepted arc

### Secand/Chord Intersection Theorem-w

If two secants or chords intersect on the interior of a circle then the measure of each angle formed is half the sum of the measure of the sum of the two measures