Download geometry_terms_-_2007

Geometry
Line
Never ending
(NO NOTES)
↔
Line Segment
Has two endpoints
(NO NOTES)
●▬●
Point
A place on a line
(NO NOTES)
●
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