April 03, 2012
Tangents
Goal:
· Apply theorems that relate tangents and
radii.
From our lesson yesterday and previous knowledge....what is
true about a tangent and a radius if they intersect?
April 03, 2012
Construct circle P on patty paper.
Choose a point outside the circle and call it N.
Draw two different rays starting at N that are
tangent to the circle. Label the two points of
tangency as Y and Z.
What do you notice about segments NY and NZ?
Tangents to a circle from the same point
are ______________.
April 03, 2012
A line that is tangent to each of two coplanar circles are called common
tangents.
Common Internal Tangents
Common External Tangent
CIT intersects the line segment
that joins the center of the
circles.
CET does not intersect the
line segment that joins the
center of the circles.
Tangent circles - coplanar circles that are tangent to the same line at the
same point.
Externally Tangent
Internally Tangent
April 03, 2012
Examples:
1. If OR = 7 and OT = 24 then RT = _____.
2. If m<R = 45 and OT = 4, then RT = ______.