A line that is tangent to the circle is a [b]line that touches (intersects) the circle at exactly one point.[/b] That's it - no more, no less, only one. [br][br]A tangent to Circle A has been created in the diagram below. [br][b]Move the the point of tangency (the point where the line touches the circle) around the circle and pay close attention to the measure of [/b][math]\angle ABC[/math][b] as you move it around[/b]. [br][br]This is your first important property of tangent lines.
What is the angle for [math]\angle[/math]DBA ?
We can make a conclusion that line DC is _________________________ to line AB.
Use the diagram below to investigate what happens when two tangents from the same circle intersect. [br][br]In this diagram, you can [b]move the intersection point (D) and point B. [/b][br]Observe the measurement of CD and DB.
When we have two tangent lines meet at an intersecting point D, the length of the tangent lines CD is __________ to DB.
When we have two tangent lines meet at an intersecting point D, the angle BDA is __________ to the angle CDA.