Unit 3 Math
Word/Vocabulary
Example/Picture
Concept #1 – Data Collection – Lessons 3.1 – 3.2
Explain
An official count
of a country’s
population. It is
conducted
every 10 years.
census
Concept #2 – Angle Measures – Lessons 3.3 – 3.5
Acute angle
Any angle that
measures
smaller than
90⁰.
Obtuse angle
Any angle that
measures larger
than 90 degrees
– but less than
180⁰.
Any angle that
measures
exactly 90⁰.
Right angle
Straight angle
Any angle that
measures 180⁰
– a straight line.
Reflex angle
Any angle that
measures larger
than 180⁰ but
less than 360⁰.
Indicated by an
arc.
Unit 3 Math
Vertical Angles
Adjacent
Angles
Vertex
Plural - vertices
Radius (R)
Plural – radii
When two lines
intersect, the
angles that do
not share a
common side.
(opposite). They
have equal
measures.
Angles that are
next to each
other – they
have a common
vertex and a
common side.
The meeting
point - sides of
an angle, sides
of a polygon, or
the edges of a
polyhedron.
A line segment
from the center of
a circle (or sphere)
to any point on
the circle (or
sphere).
Diameter (D)
The length of the
line that passes
through the
center of a circle
or sphere and has
endpoints on the
circle/sphere.
Unit 3 Math
(D= 2R)
Circumference
The distance
around a circle;
the perimeter of a
circle.
Concept #3 – Properties of Polygons – Lessons 3.6 – 3.11
Equilateral
triangle
A triangle with
all three sides
equal in length.
Each angle
measures 60⁰.
Isosceles
triangle
A triangle with
at least two
sides equal in
length.
Scalene triangle
A triangle with
all 3 sides the
same is also an
isosceles – but
is usually called
an equilateral
triangle.
A triangle with
all three sides
having different
lengths.
Unit 3 Math
Right triangle
A triangle with a
right angle.
Tessellation
A pattern of
shapes that
covers a surface
completely
without
overlaps or
gaps.
A 2 dimensional
figure formed
by three or
more line
segments
(sides) that
meet only at
their endpoints
(vertices). The
sides may not
cross one
another.
A polygon in
which all sides
and all angles
are equal.
Polygon
Regular
polygon
Unit 3 Math
polyhedron
A 3 dimensional
figure formed
by polygons
with their faces
and having no
holes.
Convex polygon
A polygon in
which all
vertices are
“pushed
outward”. Each
inside angle
measures less
than 180⁰.
A polygon in
which at least
one vertex is
“pushed in”. At
least one angle
measures
greater than
180⁰.
A polygon that
has four angles.
Concave
polygon
Quadrangle
Also known as
Quadrilateral
Parallelogram
A quadrilateral
with two pairs
of parallel sides.
Opposite sides
are congruent.
Opposite angles
are equal.
Unit 3 Math
Congruent
Having the
same shape and
size. 2
dimensional
figures are
congruent
when they
match exactly if
placed on top of
each other (one
may need to be
flipped)
Pentagon
A 5 sided
polygon.
Perimeter
The distance
around the
boundary of a 2
dimensional
shape.
P=2 * (l + w)
Parallel lines
Lines in a plane
that never meet
– they stay the
same distance
apart.
Total Degrees:
Any triangle – 180 ⁰
Straight Line – 180 ⁰
Circle – 360 ⁰
Quadrangle - 360⁰
Pentagon - 540⁰
Hexagon - 720⁰
Unit 3 Math
Heptagon - 900⁰