Circle lingo

radius

line seg from center to any point on circle

chord

line seg WITH ENDPOINTS on circle

diameter

chord going thru center d=2r

tangent

* intersects the circle at only one point, like its just grazing the edge.
* dont contain a chord
* perpendicular to radius at intersection point

secant

intersects circle at 2 points- contain a chord

central angle

angle with vertex at center

inscribed angle

angle with vertex on circle and sides contain chords

minor arc

2 point name, arc less than half of circle

major arc

3 point name, arc thats more than half of a circle

intercepted arc

arc in interior of inscribed angle and has same endpoints

circumference

2(pi)r or (pi)d or (pi)d^2/4

Area

2(pi)r^2