Using the Tangent-Chord Theorem, it is simple to prove the third theorem which provides a relationship between lines in circles - the Tangent-Secant Theorem (the other two being the Intersecting … [Read more...] about Tangent-Secant Theorem

# 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.*

## Tangents to a circle and inscribed angles

Today we'll find the angles of a triangle formed by two tangent lines to a circle using inscribed angles, and theorems about the sum of angles in a polygon. In this geometry problem, we will … [Read more...] about Tangents to a circle and inscribed angles

## Tangent Line to a Circle

A line tangent to a circle is a line from a point outside the circle that touches the circle at exactly one point. At that point, the tangent line is perpendicular to the circle's radius and diameter, … [Read more...] about Tangent Line to a Circle

## The Two Tangent Theorem

The two tangent theorem states that if we draw two lines from the same point which lies outside a circle, such that both lines are tangent to the circle, then their lengths are the same. We will now … [Read more...] about The Two Tangent Theorem