Download GEOMETRY VOCABULARY

GEOMETRY VOCABULARY
SCALE
scale - ratio between two sets of measurements
scale factor – the ratio used to enlarge or reduce similar figures
example: on a map, the scale may be 1” = 15 miles
scale drawing – a drawing that uses a scale to make an object smaller or larger than the original
examples: maps, blueprints
dimensions – measurements describing the size of an object example: a standard piece of paper is 8 ½ by 11 inches
similar figures – two figures that have exactly the same shape, but not necessarily the same size
Similar triangles
ANGLES
angles – two rays, meeting at an endpoint, or an intersection of lines, called a vertex
angle naming schemes - 1 letter, angle a:
a / abd is in blue
3-letters, naming points, the middle letter is always the vertex!!
b
a
d
vertex
complementary angles – 2 adjacent angles that measure a total of 90°
c
vertex
complementary angles
supplementary angles – 2 adjacent angles that measure a total of 180°
a
b
(also called a LINEAR PAIR, since they form a line)
ex: a and b are supplementary angles
and adjacent angles and a linear pair
vertical angles– 2 angles opposite each other, they are always congruent
x and y are vertical angles
x
y
adjacent angles– 2 angles next to each other, they share a ray
parallel lines– two lines that are equidistant from each other, they never cross
perpendicular lines– two lines that meet at a 90° angles
parallel lines
perpendicular lines, the box indicates a 90° angle
AREA, VOLUME & SURFACE AREA
right rectangular prism – 3-D figure, 6-sided, base and all sides are rectangles, all sides meet at 90° angle
right triangular prism – 3-D figure, 5-sided, base is a triangle, sides are rectangles and they
meet the base at 90° angle (looks like a tent)
net of a triangular prism
area – the space inside a 2-D figure, measured in “square” units
surface area – the space that covers a 3-D figure, measured in “square” units
net – the surface area of a 3-D figure, opened-up into a 2-D figure
net of a cube
volume - the space inside a 3-D figure, measured in “cubic” units
CIRCLES
circumference – the distance around a circle, formula: C = π d OR C = 2 r π
radius – the distance from center to edge of circle, or half way across a circle, or half of the diameter
diameter – the distance across a circle, going through its center
∏ (pi) – the ratio of circumference divided by diameter, approximately 3.14
radius
diameter
TRIANGLES & GEOMETRIC CONSTRUCTIONS
geometric construction – fun, fun, fun!!! Creating a geometric figure under given conditions, using compass, ruler, protractor, etc.
obtuse triangle – a triangle with one angle measuring greater than 90°
acute triangle – a triangle with all three angles measuring less than 90°
right triangle – a triangle with one angle measuring exactly 90°
obtuse triangle
acute triangle
right triangle
equilateral triangle – a triangle with all three angles measuring 60° and all sides having equal length
equilateral triangle
scalene triangle – a triangle with all three angles, and all three sides having different measures
scalene triangle
Triangle Inequality Theorem: The lengths of any two sides of a triangle MUST be longer than the third side.
Exterior angle
Exterior Angles of Triangles: the angle between one side of a triangle and the extension of an adjacent side. It is supplementary to the interior angle
Properties: An exterior angle of a triangle is equal to the sum of the opposite interior angles. Exterior angles always add to 360°.
SLICING 3-D FIGURES
base – the bottom of a 3-D figure, often used as its descriptor: triangular prism, triangular pyramid, square pyramid
plane sections – in 7th grade, we will slice off pieces of 3-D figures, to reveal and evaluate the resulting plane section (also called cross-section)
right rectangular pyramid – A pyramid with rectangle base and triangle faces (sides) that meet at a point
pyramid face – the triangular side of a pyramid
Plane section of this right rectangular pyramid:
face
square base
If we slice off the top, horizontal to the base, we
reveal a square plane.
e