CK-12 Foundation
Ck 12: Geometry: Segments From Secants and Tangents
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to solve for missing segments created by a tangent line and a secant line intersecting outside a circle.
CK-12 Foundation
Ck 12: Geometry: Angles Outside a Circle Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to calculate angles formed outside a circle by tangent and secant lines.
Texas Education Agency
Texas Gateway: Making Conjectures About Circles and Segments
Given examples of circles and the lines that intersect them, the student will use explorations and concrete models to formulate and test conjectures about the properties and relationships among the resulting segments.
Geometry Help
Geometry Help: Tangent Lines
Explains the basic concept of congruent triangles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.