SECTION 8.1TANGENTS AND CIRCLES
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I) REVIEW
Pythagorean Theorem:
Right Triangles
Ex: Given each triangle, find the length of the missing side:
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Pythagorean Triples
A group of 3 integers that satisfy the Pythagorean formula
Ie: (3 ,4, 5) (5, 12, 13) ….
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Practice: find the length of the missing sides:
I) WHAT IS A TANGENT?
A tangent is a line that intersects a circle at exactlyone point
Tangent
Point of Tangency
Not a Tangent!!
Not a Tangent!!
Not a Tangent!!
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II) NAMING TANGENTS
When naming tangents or any line segment, use theletters at the endpoints
The line from point “A” to “C”is called a tangent:
Ex: Name all the tangents in the diagram above:
The purple line is also a tangent:
The red tangent is called:
The green tangent is called:
II) PROPERTIES OF A TANGENT
A tangent is perpendicular to the circle radius atthe point of tangency
If AC is a tangent line at point “B” then
Triangle ABO and Triangle OBC are both
right triangles!!
Angle OBA and OBC are both 90 degrees
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Two tangents from the same exterior point to a circleare equal in length
ExteriorPoint
Point “C” is theExterior Point
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PRACTICE: FIND THE MISSING SIDES
Given:
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