# Geometry Vocab Quiz 3/2/2010

## 19 terms

### central angle

an angle whose vertex is the center of a circle and whose sides contain radii

### arc

formed by 2 points on the circle and the continuous part of the circle between the 2 points (called endpoints)

### minor arc

if m<APB is less than 180, then A and B and the points of circle P in the interior of <APB form a minor arc. measure of minor arc = measure of central angle

### major arc

the points A and B and the points of circle P that do not lie on minor arc AB form a major arc. measure of major arc = 360 - measure of its minor arc

### circle

set of points in a plane at a given distance from a given point in that plane

### semicircle

an arc whose endpoints are the endpoints of a diameter, 180 degrees

### congruent circles

two circles are congruent if they have the same radius

### congruent arcs

two arcs of the same circle or congruent circles are congruent if they have the same measure ***TWO minor arcs of the same circle or of congruent circles are congruent if their central angles are congruent

### center

the given point in a circle

given distance in a circle, any segment that joins the center to a point of the circle is called a radius

### chord

a segment whose endpoints lie on a circle

### secant

line that contains a chord

### diameter

chord that contains the center of a circle

### tangent

line in the plane of a circle that intersects (90 degree angle) the circle in exactly one point

### point of tangency

where tangent intersects the circle in exactly one point

### sphere

the set of all points in space at a distance r from point O

### concentric circles

circles that lie in the same plane and have the same center

### concentric spheres

spheres that have the same center

### inscribed / circumscribed

when each vertex of the polygon lies on the circle