D is the midpoint of AC and E is the midpoint of AB.

Find x, the length of segment DE, DC, and AC.

X = 4 DE = 6.5 DC = 4 AC = 8

BB

Cornell Notes

Concurrent lines

Collinear

Three or more lines that meet or intersect at one point are concurrent lines

Three or more points that are on the same line are collinear points

Acute Triangle

Obtuse Triangle

Right triangle

A triangle with three acute angle (less than 90 degrees)

A triangle with one obtuse angle (more than 90 degrees)

A triangle with one right angle ( 90 degree angle)

Turn on your calculator. Go to house, 7 (my documents). Click on 1.12. You should see a triangle with three perpendicular bisectors.

Perpendicular bisector

Circumcenter

Point where perpendicular bisectors meet

A line that is perpendicular to a segment at its midpoint

Move around vertex B to form each of the following triangles: acute, obtuse, and right. Draw sketches in your notes for each triangle.

Acute triangle:

Obtuse triangle:

Right triangle:

Where are the perpendicular bisectors concurrent?

Inside the triangle

Outside the triangle

On the triangle

Press Ctrl over to move to tab 1.2. It should say Angle bisector.

Move around vertex B to form each of the following triangles: acute, obtuse, and right. Draw sketches in your notes for each triangle.

Angle bisector

A ray that divides an angle into 2 congruent angles.

What do you notice about the incenter in each of the triangles? Where are the angle bisectors concurrent?

Incenter

Point where angle bisectors meet

The angle bisectors are always concurrent inside the triangle

Pg. 63 #7 (at least 3 different triangle) and 8

Pg. 64 # 4

Median: a segment from a vertex to the midpoint of the opposite side