An angle formed by two radii and whose vertex is at the center of the circle.
A line segment whose endpoints are on a circle.
A chord that passes through the center of the circle. The length of a diameter is two times the length of a radius.
An angle with its vertex on the circle and whose sides are chords.
The arc that is inside an inscribed angle and whose endpoints are on the angle.
point of tangency
The point where the tangent line touches the circle.
The secant of an angle in a right triangle is the value found by dividing length of the hypotenuse by the length of the side adjacent the given angle. The secant ratio is the reciprocal of the cosine ratio.
Tangents Secant Segments Theorem
If a tangent and a secant are drawn from a common point outside the circle (and the segments are labeled like the picture below), then a^2 = b(b+c).
This concept teaches students to solve for missing segments created by a tangent line and a secant line intersecting outside a circle.