63 terms

point

a definite location in space

line

a series of dots so close together that they appear as one continuous thing; there is no beginning or end to a "line".

ray

a part of a line that extends indefinitely from one direction

line segment

two endpoints and the straight path between them; a "line" with a beginning and an ending.

intersecting lines

two or more lines that meet and cross at any angle.

perpendicular lines

lines that intersect at a right angle

parallel lines

lines going in the same direction without touching; two lines (or line segments) with the same slope that are always the same distance apart.

line of symmetry

a line that divides a figure into two halves that reflect each other

congruent figures

figures that are the same size and shape

vertical

line going up and down

horizontal

lines going side to side

plane

is a flat two-dimensional surface that is unending in all directions

angle

two rays with a common endpoint

right angle

an angle that measures 90 degrees

acute angle

an angle with a measure greater than 0 degrees and less than 90 degrees

obtuse angle

an angle that measures greater than 90 degrees and less than 180 degrees

reflex angle

angle that measures more than 180 degrees and less than 360 degrees

complementary angle

if the sum of two angles measures 90 degrees

supplementary angle

if the sum of two angles measure 180 degrees

straight angle

180 degree angle

polygon

a closed figure with three or more straight sides

circumference

the distance around the edge of a circle

right triangle

a triangle with one right angle

acute triangle

triangle whose interior angles are all acute

obtuse triangle

triangle that has one angle more than 90 degrees

equilateral triangle

a triangle with three congruent sides

isosceles triangle

a triangle with two equal sides, the two base angles are also equal

scalene triangle

all sides are different

measure of the interior angles of a triangle

180 degrees

faces

the flat surfaces of a 3-D figure

edges

the intersection of faces of a 3-D figure

square

a parallelogram with all sides congruent and all angles congruent

rectangle

a quadrilateral with four right angles; opposite sides are parallel and congruent

trapezoid

a quadrilateral having two sides parallel

rhombus

a parallelogram with four equal sides

parallelogram

a quadrilateral that has both pairs of opposite sides parallel

circle

the set of all points in a plane that are the same distance from a given point

radius

the distance from the center of the circle to any given point on the circle

diameter

the distance across the circle through the center

circumference

the distance around a circle

area

the number of the square units in a figure

perimeter

the distance around any closed figure

volume

the amount of space a 3-D figure containes; the number of cubic units in a 3-D figure.

quadrilateral

a polygon with four sides

pentagon

a polygon with five sides

hexagon

a polygon with six sides

heptagon

a polygon with seven sides

octagon

a polygon with eight sides

nonagon

a polygon with nine sides

decagon

a polygon with ten sides

solid

a three-dimensional (3-D) figure

base

the bottom side of a geometric figure from which the altitude or height can be constructed

dodecagon

a 12 sided polygon

equilateral

means that all sides are equal

sum

the answer to an addition problem

difference

the answer to a subtraction problem

product

the answer to a multiplication problem

quotient

the answer to a division problem

sum of the interior angles of a polygon

(n-2)180 ; with n as the number of sides in the figure

rhombus

has four equal sides

adjacent angles

angles that share a vertex and a side but have no interior points in common

vertical angles

angles that are opposite from each other; formed from two intersecting lines

height of a figure

the perpendicular distance from the base to the opposite side of the figure (always forms a right angle with the base); also called the altitude