Chapter 2 Flashcards
Parallel Postulate
If two lines are cut by a transversal and the sum of the interior angles is less than 180 then, those two lines will intersect on that side of the transversal.
Complementary angles
90
Supplementary angles
180
Vertical angles
Opposite angles on perpendicular lines
Triangle Inequality Theorem
Decides whether it’s possible for 3 points to from a triangle. The sum of any two sides MUST be larger than the third side. If this criteria isn’t met then a triangle CANNOT be formed.
Concurrence
when 3 or more lines meet at a single point
Medians
Lines drawn from the vertices that bisect the opposite side.
Centroid
Where median lines meet, AKA center of mass
Altitudes
Perpendicular lines drawn from vertex to opposite side
Orthocenter
Where altitude lines meet
Angle bisector
Lines drawn from the angle that split the angle in half
Incenter
Where angle bisectors meet.
Perpendicular bisectors
evenly split 3 sides of the triangle
circumcenter
where perpendicular bisectors meet
Polygon
Any 2D shape with straight AND connecting lines, number of sides tells you the name
Polygon shape chart
Triangle
square
rectangle
quadrilateral
pentagon
hexagon
heptagon
octagon
nonagon
decagon
n-gon
3
4
4
4
5
6
7
8
9
10
n
Regular polygons
All sides have the same length and all angles have the same measure.
Exterior angle
The measurement between the shape and each line segment when extended past the shape
Formula: 360/n
Interior angle
The supplementary angle to the exterior angle
Formula: 180-(360/n) OR (n-2)x180/n
Finding the Area of a regular polygon
1). Split into double the amount of triangles than sides
2). find the interior angle measure and split in half. this will be angle measure for all the triangles
3). use 180 rule to find the missing two angles
4). use tangent O/A to find all info needed for A=.5bh
5). Multiply that number by however many triangles you have and put it in units squared.
