Transcript 8.1: Properties of Tangents to a Circle

What is a tangent?
 A tangent (Line AB) is a line that intersects the outside of the circle.
 The point of tangency (Point P) is where the line intersects the circle.
B
P
A
How many points of
tangency can you have
from one point?
What is the tangent-radius
property?
 A tangent-radius property is:

The line formed between the centre of the circle, O, and the point of
tangency, P, forms and 90 degree angle with the tangent line, AB.
B
P
A
O
Why is the Pythagorean
Theorem so important to
us?
 What shape do we have now?
 What is the length of C?
B
10
A
P
4
O
C
Circle Tangents
 What is a tangent?
 How is it formed?
 What is the tangent-radius property?
 How important is the Pythagorean Theorem?
 What do the interior angles of every triangle add up
to?
Circle Tangents
 The interior angles of every triangle add up to 180
degrees.
 REMEMBER:
 An isoceles triangle has two equal sides and two
equal angles.
 An equilateral triangle has three equal sides and
three equal angles
Assignment
 Pg. 388
 #3-9, 11-14,15a
 Then 17, 19