Download Geometry_Nomenclature_Definitions

1a
The very tiny dot left by a
sharp pencil is given the name
point.
1b
The very fine trace made by a
very sharp pencil is given the
name of line.
1c
A very thin sheet of tissue
paper gives us the idea of
surface.
1d
All things that occupy a place is
given the name of solid.
2a
The straight line is a direct
and unlimited line; it is a line
which
does
not
change
direction throughout its length.
2b
A curved line changes its
direction continually from point
to point.
2c
The broken line is named up of
segments not going in the same
direction and connected so
that successive segments have
an end point in common.
3a
A ray is each of the two
portions obtained by dividing a
straight line by a point.
3b
A line segment is that part of
the straight line which is
limited by two points.
3c
The point which divides that
straight line into tow rays is
given the name of origin of
each ray.
3d
The end points are the two
points that limit a line segment.
4a
A straight line is called
horizontal when it follows the
direction of still water.
4b
A straight line is called vertical
when it follows the direction of
a plumb line.
4c
A straight line is called oblique
when it follows neither the
direction of still water nor the
direction of a plumb line.
5a
Two line segments are adjacent
segments when they have only
one extremity in common and
do not lie on the same straight
line.
5b
Two
line
segments
are
consecutive segments when
they have one extremity in
common and lie on the same
straight line.
6a
Two straight lines are called
parallel when lying on the same
plane, as far as they extend,
never meet.
6b
Two straight lines are called
divergent when they go away
from each other; therefore,
the distance between them
increases.
6c
Two straight lines are called
convergent when they approach
each other; therefore, the
distance
between
them
decreases.
6d
Two straight lines which cross
each other are called oblique
when the angles formed by
them are not equal.
6e
Two straight lines are called
perpendicular when meeting
each other they form four
right angles.
6f
The perpendicular straight line
drawn through the midpoint of
a line segment is called the
perpendicular bisector.
7a
An angle is each part of a plane
limited by two rays having a
common origin.
8a
When the ray after wheeling a
complete turn is superimposed
on the other ray, it forms an
angle called whole angle.
8b
When two rays forming an
angle are a prolongation of
each other, they form a
straight angle.
8c
The angle that is half of the
straight angle is called a right
angle.
8d
When an angle measures less
than a right angle, it is called
an acute angle.
8e
When an angle measures more
than a right angle, it is called
an obtuse angle.
9a
The Vertex of an Angle is the
common point where the two
rays forming an angle originate.
9b
The sides of an angle are the
two rays that form an angle.
9c
The measurement of an angle is
given the name size and is
expressed in degrees.
9d
A ray that divides an angle into
two equal parts is called
bisector.
10a
An angle which is smaller than a
straight angle is said to be a
convex angle.
It does not
contain the prolongation of its
sides.
10b
An angle which is greater than
a straight angle but less than a
whole angle is said to be a
reflex angle. It contains the
prolongations of its sides.
12a
Two angles whose sum is equal
to a right angle and therefore
equal to 90º are called
complimentary angles.
12b
Two angles whose sums are
equal to a straight angle and
therefore are equal to 180º are
called supplementary angles.
12c
When two angles are both
adjacent and complementary,
they are called adjacent
complimentary angles.
11a
Angles having a vertex and one
side
common
are
called
adjacent angles.
12d
When two angles are adjacent
and complimentary, they are
called adjacent complimentary
angles.
11b
The opposite non adjacent
angles
formed
by
two
intersecting straight lines are
called vertical angles.
13a
The angles formed on the inner
side of two straight lines cut
out by a transversal are called
interior angles.
13b
The angles formed on the outer
side of two straight lines cut
by a transversal are called
exterior angles.
13c
Interior
angles
lying
on
opposite
sides
of
the
transversal are called alternate
interior angles.
13d
Interior angles lying on the
same side of the transversal
are called interior angles on
the
same
side
of
the
transversal.
13e
Exterior
angles
lying
on
opposite
sides
of
the
transversal are called alternate
exterior angles.
13f
Exterior angles lying on the
same side of the transversal
are called exterior angles on
the
same
side
of
the
transversal.
13g
Two angles, one interior the
other exterior, each on one of
the two straight lines and lying
on the same side of the
transversal
are
called
corresponding angles.
14a
Any figure bounded by a
broken straight line is called a
polygon.
14b
A plane figure bounded by a
closed curved line is called a
simple closed curve.
15a
A polygon bounded by three
line segments is called a
triangle.
15b
A polygon bounded by four line
segments
is
called
a
quadrilateral.
15c
All the polygons limited by
more than four line segments
retain the general name of
polygon, but each takes its
particular name according to
the number of its line
segments.
16a
The plane figure similar to an
egg is given the name of oval.
16b
The plane figure similar to an
oval having the two minor arcs
equal is given the name of
ellipse.
16c
Any triangle having arcs for its
sides is called a curvilinear
triangle.
16d
The plane figure limited by a
cured line having all the points
equidistant from a fixed point
is given the name of circle.
17a
The triangle with all its sides
unequal is called a scalene
triangle.
17b
The triangle with two sides
equal is called an isosceles
triangle.
17c
The triangle with all of its
sides equal is called an
equilateral triangle.
18a
The triangle that has one right
angle is called a right-angled
triangle.
18b
The triangle that has one
obtuse angle is called obtuseangled triangle.
19e
Each part of the plane enclosed
between two consecutive sides
of a triangle is called an angle.
18c
The triangle with all three
angles acute is called acuteangled triangle.
19f
The point where two sides of a
triangle meet is called the
vertex.
19a
The part of the plane limited
by the sides of a triangle is
called surface.
19g
The line segment from any one
vertex of the triangle, drawn
perpendicular to the opposite
side, is called its altitude.
19b
The line segments which bound
a triangle are called its sides.
19c
The side opposite to each
vertex may be considered as a
base.
19d
The total of the sides of a
triangle is called its perimeter.
19h
A line segment joining a vertex
to the midpoint of the opposite
side is called the median.
19i
The perpendicular line drawn
through the midpoint of a side
is called the perpendicular
bisector of a side of the
triangle.
19j
The bisector drawn from the
vertex of an angle of a triangle
to the opposite side is called an
angle bisector of the triangle.
20a
In a right-angled triangle the
side opposite the right angle is
called the hypotenuse.
20b
In a right-angled triangle the
sides forming the right angle
are called legs.
21a
When the legs of a rightangled triangle are equal, the
triangle is a right-angled
isosceles triangle.
22a
A quadrilateral which has no
parallel sides is given the name
of common quadrilateral.
22b
A quadrilateral which has only
two opposite sides parallel is
called a trapezoid.
22c
A quadrilateral whose opposite
sides are parallel is called a
parallelogram.
22d
The parallelogram which has all
right angels is called a
rectangle.
22e
The parallelogram which has
four equal sides is called a
rhombus.
22f
The quadrilateral which has
four equal sides and four right
angles are called a square.
22g
A kite is a quadrilateral with
two pairs of equal adjacent
sides.
One diagonal is the
perpendicular bisector of the
other diagonal.
23a
The part of the plane enclosed
inside the parallelogram is
called a surface.
23b
The line segments which bound
a parallelogram are called the
sides.
23c
Each side of a parallelogram
takes the name of base.
23d
The total of the sides of a
parallelogram is called the
perimeter.
23e
Each part of the plane enclosed
between two consecutive sides
of the parallelogram is called
an angle.
23f
The points where two sides of
a parallelogram meet are called
vertices.
23g
The perpendicular distance
between opposite sides is
called the altitude.
23h
Each line segment that joins
opposite
vertices
of
a
parallelogram is called the
diagonal.
24a
The part of the plane enclosed
inside the rectangle is called
the surface.
24b
The line segments which bound
a rectangle are called the
sides.
24c
Each side of the rectangle
takes the name of base.
24d
The total of the sides of the
rectangle
is
called
the
perimeter.
24e
Each part of the plane enclosed
between two consecutive sides
of the rectangle is called an
angle.
24f
The points where two sides of
a rectangle meet are called
vertices.
24g
The perpendicular distance
drawn between two opposite
sides of a rectangle is called
the altitude.
24h
Each line segment which joins
opposite
vertices
of
a
rectangle is called the diagonal.
25a
The part of the plane enclosed
inside the rhombus is called
the surface.
25b
The line segments which bound
a rhombus are called the sides.
25c
Each side of the rhombus takes
the name base.
25d
The total of the sides of the
rhombus
is
called
the
perimeter.
25e
Each part of the plane enclosed
between two consecutive sides
of the rhombus is called an
angle.
25f
The points where two sides of
a rhombus meet are called
vertices.
25g
The perpendicular distance
drawn between two opposite
sides of a rhombus is called the
altitude.
25h
Each line segment which joins
opposite vertices of a rhombus
is called the diagonal.
26a
The part of the plane enclosed
inside the square is called the
surface.
26b
The line segments which bound
a square are called the sides.
26c
Each side of the square takes
the name base.
26d
The total of the sides of the
square is called the perimeter.
26e
Each part of the plane enclosed
between two consecutive sides
of the square is called the
angle.
26f
The points where two sides of
a square meet are called the
vertices.
26g
The perpendicular distance
drawn between two opposite
sides of a square is called the
altitude.
26h
Each line segment which joins
opposite vertices of a square is
called the diagonal.
27e
The total of the sides of a
trapezoid
is
called
the
perimeter.
27a
The part of the plane enclosed
inside the trapezoid is called
the surface.
27f
The parts of the plane
enclosed
between
two
consecutive
sides
of
a
trapezoid are called angles.
27b
The line segments which bound
a trapezoid are called the
sides.
27c
The parallel sides of the
trapezoid are called its bases.
The longest is called the major
base and the other is called
the minor base.
27d
The two nonparallel sides of a
trapezoid are called oblique
sides.
27g
The points where two sides of
a trapezoid meet are called
vertices.
27h
The perpendicular distance
drawn between the parallel
sides of a trapezoid is called
the altitude.
27j
The line segment connecting
the
midpoints
of
the
nonparallel sides of a trapezoid
is called the median.
27k
The joining line of the
midpoints of the parallel sides
is the line segment connecting
the midpoints of the bases of a
trapezoid.
28a
The trapezoid which has two
nonparallel unequal sides is
called scalene.
28b
A trapezoid whose nonparallel
sides are equal is called
isosceles.
28c
A trapezoid having one of its
nonparallel sides perpendicular
to its base is called rightangled.
28d
The trapezoid in which the
obtuse angles are opposite is
called obtuse-angled.
29a
To a polygon having the sides
and angles unequal is given the
name irregular polygon.
29b
An equiangular polygon with
unequal sides is called an
irregular equiangular polygon.
29c
An equilateral polygon with
unequal angles is an irregular
equilateral polygon.
29d
A polygon having the sides and
angles equal is called a regular
polygon.
30a
The regular polygon with three
sides is called an equilateral
triangle.
30b
The regular polygon with four
sides is called a square.
30c
A polygon having five sides is
called a pentagon.
31b
The line segments which bound
a polygon are called the sides.
30d
A polygon having six sides is
called a hexagon.
31c
The total of the sides of a
polygon
are
called
the
perimeter.
30e
A polygon having seven sides is
called a heptagon.
30f
A polygon having seven sides is
called an octagon.
30g
A polygon having seven sides is
called a nonagon.
30h
A polygon having seven sides is
called a decagon.
31a
The part of the plane enclosed
inside the polygon is called the
surface.
31d
Each part of the plane enclosed
between two consecutive sides
of the polygon is called the
angle.
31e
The points where two sides of
a polygon meet are called the
vertices.
31f
A line segment drawn from one
vertex to another, that is not
consecutive, is called the
diagonal.
31g
The point which is equidistant
from all the vertices and from
all the sides is given the name
center.
32c
A line segment joining the
center to any point on the
circumference is called the
radius.
31h
The line segment drawn from
the center of a polygon to one
of its vertices is called the
radius.
32d
A line segment joining any two
points on the circumference is
called the chord.
31i
The perpendicular line segment
drawn from the center of the
regular polygon to one of its
sides is called the apothem.
32a
The part of the plane within
the outline of the circle is
called the surface.
32b
The fixed point within the
circle from which all points of
the
closed
curve
are
equidistant
is
called
the
center.
32e
A line segment passing though
the center and having the
circumference as end points is
called the diameter.
32f
The closed curve whose points
are equidistant from the
center and which limits the
circle
is
called
the
circumference.
32g
A part of the circumference
limited by two points is called
the arc.
32h
Each of the two equal parts
obtained by dividing the
circumference
along
the
diameter is called the semi
circumference.
32i
Each part of a circle formed by
a diameter is called a semi
circle.
32j
The figure formed by two radii
and intercepted arc is called a
sector of a circle.
33b
A straight line that meets the
circumference at one point only
is called a tangent.
33c
A straight line that intersects
the circumference at two
points is called a secant.
34a
Two circumferences having no
point in common one being
outside the other are called
external.
32k
The figure formed by a chord
and its arc is called a segment
of a circle.
34b
Two circumferences having no
point in common one being
inside the other are called
internal.
33a
The straight line having no
point in common with the
circumference is called the
external.
34c
Two circumferences having only
one point in common and being
external to each other are
called externally tangent.
34d
Two circumferences having one
point in common but one being
internal to the other are called
internally tangent.
34e
Two circumferences having two
points in common are called
secants.
34f
Circles having the same center
are called concentric.
34g
The part of the plane enclosed
between
two
concentric
circumferences
is
called
annulus.