# Geometry Vocabulary 2

## Terms

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Angle
Corner formed by the intersection of 2 line segments, rays, or lines
Area
Space occupied by a 2D figure
Base
The # in a expression that has a power or exponent above it; the line or plane upon which a geometric firgure is thought of as resting.
Circumference
The distance measured by the line bounding a circle
Complement
For any event E, there is a corresponding event consisting of all the outcomes not in E.
Complementary angles
2 angles whose measures total 90 degrees
Cone
A 3D figure with a circular base and the top meeting at a vertex; it resembles a funnel.
Congruent
2 measures with the exact same value
Cross-multiplying
Multiplying the denominator of one ratio in a proportion by the numerator in the other ration and vice versa.
Cylinder
A 3D figure with 2 circular bases; resembles a can
Deca
Metric prefix meaning "ten"
Decagon
a ten sided polygon
Deci
Metric prefix meaning "one-tenth"
Denominator
the bottom number in a fraction; it idicates into how many parts the whole is divided.
Dodecagon
a 12 sided polygon
Edge
a line or line segment at which 2 plane surfaces meet
Face
anyone of the surfaces of a geometric figure
Heptagon
a 7 sided polygon
Hexagon
a 6 sided polygon
Hyptenuse
The longest side of a right triangle, located opposite the right angle
Icosagon
a 20 sided polygon
Interest
Money paid for the use of money expressed as a percentage per unit of time
Line
Continuously connected points extending to infinity
Line segment
Continously connected points with 2 distinct start and end points
Liter
Metric unit of measure for volume or capacity
Milli
Metric prefix meaning "one- thousandth"
Nonagon
a 9 sided polygon
Obtuse angle
An angle whose measure is greater than 90 degrees
Octagon
An 8 sided polygon
Orderd pair
the x- axis coordinate and the y- axis coordinate (x, y)
Parallelogram
a quaderlateral w/ both pairs of opposite sides parallel
Pentagonal prism
a prism with 2 pentagonal bases
Pentagonal pyramid
a pyramid with a pentagonal base
Perimeter
distance around a figure
Pi
the ratio of a circumference of a cirlce to its diameter; the aprox. value is 3.14
Polygon
a closed plane figure; 2D figure
Polyhedron
a solid figure; 3D figure
Principal
the amount of debt or investment minus the interest
Prism
a 3D object with rectangles for sides or faces
Probability
A # from 0 to 1 that states the likelihood an event will occur
Proportion
an equation with 2 equal ratios on each side of the equal sign
Pyramid
a 3D figure with triangles for sides or faces
a 4 sided polygon
A straight line extending from the center of the circle or sphere to the periphery
Ratio
a comparison of 2 #'s; can be written in the form 1/4 1:4 or 1 to 4
Ray
A line extending in one direction from a fixed point
Reciprocal
THe inversion of a fraction (the numerator becomes the denominator and the denominator becomes the numerator)
Rectangle
a parallelogram with 90 degree angles
Rectangular Prism
a prism with 2 rectangular bases
Rectangular pyramid
a pyramid with a rectangular base
Regular
a 2D figure with all sides the same length and all angles the same measure
Rhombus
a parallelogram with sides of equal length
Right angle
an angle whose measure is exactly 90 degrees
Right triangle
a triangle with one right angle
Rise
how many units up or down a line travels on a graph b/w 2 points
Run
how many units left or right a line travels on a graph b/w 2 points
Scale
A form of ratio often used in maps or models where the first number is the dimension of the map or model and the 2nd # is the dimension of the actual object; written in the form 1:4
Simple interest
found by multiplying the principal by the annual interest rate and then multiplying the result by the # of years or time; i= p*r*t
Similar triangles
if each side of 1 triangle can be multiplied by the same # and the result is the length of each side of a second triangle
Slant height
The height of a lateral side in a 3D figure
Slope
Ratio of the rise to the run
Sphere
a 3D figure that is completely circular in width and height; looks like a hollow ball
Square
a parallelogram with 90 degrees and sides of equal length
Trapezoid
a quadrilateral with only 1 pair of opposite sides parallel
Triangle
a 3 sided figure
Triangular prism
a prism with 2 triangular bases
Triangular pyramid
a pyramid with a triangular base
Vertex
the point where an angle is formed; the corner point of a geometric figure
Vertical angles
opposite angles formed when 2 lines or line segments intersect; the angle measures are congruent
Volume
space occupied by a 3D figure
Supplementary angles
2 angles whose measures total 180 degrees
Surface Area
Sum of the area of each base and face of a 3D figure

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