Tangent Lines

A straight line outside a circle which just "touches" the circle, and intersects it at exactly one point, is called a tangent line.

The tangent line is perpendicular to the radius at the point where it intersects the circle.

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Now that we've explained the basic concept of tangent lines in geometry, let's scroll down to work on specific geometry problems relating to this topic.

Prove that the Tangent is Perpendicular to the Radius

Tangent-Secant Theorem

Tangents to a circle and inscribed angles

Tangent Line to a Circle

The Two Tangent Theorem