Definition of a Circle
A collection of points equidistant from a single point
A radius is a segment...
which connects the center of a circle with a point on the circle
in a circle are congruent
A diameter is a chord...
which passes through the center of a circle
The length of a diameter...
is twice the length of a radius
A line which intersects the circle...
in exactly one point (the point of tangency) is called a tangent line
A tangent is perpendicular to...
the radius which intersects it at the point of tangency
A semicircle is an...
arc whose endpoints are the endpoints of a diameter
If an angle is inscribed...
in a semicircle, then it is a right angle