Section 1.5 Special Points in Triangles
CONCURRENT The point where 3 or more lines intersect
What are some things you already know about triangles or circles? TRIANGLES & CIRCLES What are some things you already know about triangles or circles?
PREVIOUS FACTS… How many sides does a triangle have? What kinds of triangles are there?
WHAT IS A PERPENDICULAR BISECTOR??
PERPENDICULAR BISECTOR Forms right angles. Splits the segment in half
PERPENDICULAR BISECTORS & TRIANGLES Now let’s combine perpendicular bisectors and triangles.
BEGIN BY… Finding the perpendicular bisector of each side of the triangle.
WHAT CAN WE CONCLUDE? What happens when these 3 lines intersect? What is formed?
Perpendicular Bisectors The perpendicular bisectors of a triangle ____________ at a single __________.
EXAMPLE
CIRCUMCENTER The intersection point of the perpendicular bisectors of a triangle
Circumcenter of an Obtuse Triangle
WHAT IS A ANGLE BISECTOR??
ANGLE BISECTOR Splits the angle in half
ANGLE BISECTORS & TRIANGLES Now let’s combine angle bisectors and triangles.
BEGIN BY… Finding the angle bisector of each angle of the triangle.
WHAT CAN WE CONCLUDE? What happens when these 3 lines intersect? What is formed?
Angle Bisector The angle bisectors of a triangle __________ at a single _________.
EXAMPLE
INCENTER The intersection point of the angle bisectors of a triangle
INSCRIBED & CIRCUMSCRIBED CIRCLES
INSCRIBED Inside the triangle Just touches the three sides of the triangle.
INCENTER The center of an inscribed circle Another definition of Incenter: The center of an inscribed circle
CIRCUMSCRIBED Outside the triangle Contains all 3 vertices
CIRCUMCENTER The center of a circumscribed circle
A couple of other definitions you need to know
Altitude A perpendicular line segment from a vertex of a triangle to the line containing the opposite side. How many altitudes can a triangle have?
Median A line segment from a vertex to the midpoint of the opposite side.
Centroid The point where the 3 medians meet