Geometry
Line
Never ending
(NO NOTES)
↔
Line Segment
Has two endpoints
(NO NOTES)
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Point
A place on a line
(NO NOTES)
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Plane
An area with geometric figures
Also called a coordinate plane
Ray
Consist of an endpoint and a line
Used to create angles
→
Angle
Consist of two rays that meet at a vertex
(NO NOTES)
∟
Vertex
The point that two rays have in common
Used to form angles and polygons
Acute
An angle less than 90 degrees
Used to classify angles and triangles
Right
An angle that measures exactly 90
degrees
Used to classify angles and triangles
Obtuse
An angle that measures greater than 90
degrees but less than 180 degrees
Used to classify angles and triangles
Triangle
Consist of three angles that when added
equals 180 degrees
A= 45, B = 45, C = 90
A + B + C = 180
45 + 45 + 90 = 180
180 = 180
Quadrilateral
Is made of four segments that intersect
only at their endpoints
Has four vertices that when added equals
360 degrees
Congruent Segments
Have equal lengths
Used to classify polygons
Congruent Angles
Have equal measures
Used to classify polygons
Straight Angle
An angle that measures exactly 180
degrees
A straight line
Reflex Angle
An angle that measures more than 180
degrees but less than 360 degrees
Pay attention to notation (angle symbol)
Complementary Angles
Two angles that add up to 90 degrees
Calculate by subtracting the given angle
from 90
Supplementary Angles
Two angles that add up to 180 degrees
Calculate by subtracting the given angle
from 180
Vertical Angles
Angles opposite each other when two
straight lines cross
(NO NOTES)
Perpendicular Lines
When two lines meet or cross at a right
angle
(NO NOTES)
Parallel Lines
Lines that run side by side and never
cross
(NO NOTES)
Transversal Line
A third line that crosses two parallel lines
(NO NOTES)
Equilateral Triangle
Has three equal sides and three equal 60
degree angles
(NO NOTES)
Isosceles Triangle
Has two equal sides and two equal angles
called base angles, the third angle is
called the vertex angle
(NO NOTES)
Scalene Triangle
Has no equal sides and no equal angles
(NO NOTES)
Right Triangle
An isosceles or scalene triangle that has a
90 degree angle
(NO NOTES)
Similar Triangles
Have the same shape but not necessarily
the same size
Differ only in the lengths of their sides
All angles are equal
Corresponding Sides
Sides or angles that have the same
relative position
The sides that are opposite the equal
angles
The corresponding sides can be written as
a proportion
Square
Of a number, is that number multiplied by
itself
6 is the base and 2 is the exponent
6 is called the factor
6 x 6 = 36
62
Perfect Square
Numbers that have whole numbers as
their square roots
(NO NOTES)
Example: 152 = 225
Square Roots
Symbol √ (radical)
Think: What number times itself equals
this number?
Example √25 = 5
Hypotenuse
In a right triangle the side opposite the
right angle
(NO NOTES)
Pythagorean Theorem
Relationship between the hypotenuse and
the two shorter sides
Formula – c2 = a2 + b2
Circle
Figure with all points the same distance
from the center
Equals 360 degrees
Radius
From the center of the circle to the side
Symbol – r
Equals ½ of the diameter
Diameter
Distance across the circle, from side to
side going through the center
Symbol – d
Equals two times the radius
Circumference
The distance around the circle
Formulas
Radius – C = 2∏r
Diameter – C = ∏d
Pi
Greek letter
∏
Approximate value is 3.14 or 22/7
Area
Measure of surface, measured in square units
Formulas
Rectangle – A=lw
Square – A =s2
Triangle – A = 1/2bh
Circle – A = ∏r2
A = lw
A=6 * 10
A = 60 squared units
Volume
Measure of the space taken by a solid object
measured in volume units (cubic)
most common shape is the rectangular solid
Formulas
Rectangular solid V= lwh
Cylinder V = ∏r2h
Example
l=4, h = 2, w= 1
V=lwh
V=4*2*1
V=8 cubic inches
Perimeter
Distance around a shape
Formula
Square -- P = 4s
Rectangle -- P = 2l + 2w
Triangle –- P = s + s + s
Example
P=4s
P=4*4
P=16 inches