# Properties of Tangents

- Author:
- James McKee

- Topic:
- Circle, Geometry, Tangent Line or Tangent

## Instructions for Part 1

Construct radius AB. Measure the angle between the radius and the tangent. Try moving point B around the circle and observe the measure of the angle.

What do you notice about the angle between the tangent line and the radius drawn to the point of tangency?

## Instructions for Part 2

Use the distance measurement tool to measure the lengths of segments EC and DC. Move point C around the outside of the circle to explore the relationship between the lengths of the two segments.

What do you notice about the lengths of the two segments EC and DC?

## Instructions for Part 3

Measure angles EAD and DCE. Move point C around the outside of the circle to explore the relationship between these two angles.

What is the relationship between the angle between the two tangent segments and the corresponding central angle?