7 Math Vocabulary # 6b (2D Geometry ­ Perimeter and Area).notebook
Perimeter
7th Grade Math Vocabulary
2D Geometry: Perimeter and Area
Ahrens
The distance around an object.
side 3
side 2
side 1
P= side 1 + side 2 + side 3
2D Geometry (Perimeter and Area) Glossary
To fence in this rectangular yard, you would measure the perimeter.
w
l
P=2l+2w
Perimeter
Area
Square Units
The size of a surface. The number of square units it takes to cover a surface.
A measurement in the shape of a square with side lengths that are one unit long. 1 unit
1 unit x 1 unit = 1 square unit
2 units
30u x 10u = 300u2 + 20u x 10u = 200u2
500u2
3 units
1 units 1 units
3 units
3 units x 3 units = 9 units2
3 units
1 unit
3 units
3 units
Notation:
sq unit
unit2
u2
Area
Square Units
Vertex
Vertex
A point where two or more straight lines meet.
Point where two or more straight lines/faces/edges meet.
A
Point A or vertex A
Vertex
vertex
vertex
B
C
vertex
A corner. d un
fo es!
o
Als angl
in A
The plural of vertex is "vertices"
3 units x 3 units = 9 units2
A triangle has 3 vertices.
Vertex
1
7 Math Vocabulary # 6b (2D Geometry ­ Perimeter and Area).notebook
Altitude
Base & Height
A line segment from a vertex of the triangle and perpendicular to the opposite side. The height.
h
Base­ the surface Height­ the distance that a solid object from the base to the top of a solid object.
stands on
height
h
b
b
h
base
This is not the height. It is not perpendicular to the base. b
Ahrens
height
The base and height always form a right angle.
base
Altitude
Base & Height
Diagonal
Dimensions
A measurement of length in one direction.
A line that goes from one non­
adjacent vertex to another.
1 dimension
Cannot draw a diagonal, because all vertices are adjacent.
2 dimensions
length
3 dimensions
Diagonal
Dimensions
Formula
Parallelogram
An equation that describes a certain relationship between variables. Area=length width
l
3
d=rt
A = lw
4
distance=rate time
A = lw
A = 5 8
A = 40u2
w
5
8
Formula
A quadrilateral with opposite sides that are both congruent and parallel. C=d
circumference=diameter E=mc
2
energy=mass speed of light2
A rhombus is a parallelogram with both sets of opposite sides . 2
1
Four sides
Opposite sides
Opposite sides //
Parallelogram
2
7 Math Vocabulary # 6b (2D Geometry ­ Perimeter and Area).notebook
Ahrens
Irregular Figure
Trapezoid
A quadrilateral with one pair of parallel sides.
Not regular; a regular figure is a polygon with all congruent sides and angles, or a polyhedron with all regular faces.
regular
regular
equilateral
equiangular
There are no // sides.
Trapezoid
regular
equilateral
irregular
irregular
equiangular
right
scalene
isosceles
irregular
not equilateral
not equilangular
Irregular Figure
3