Grade 8 Geometry

Question 1

pyramid

Answer 1

polygon for a base and triangular sides

pyramids are named by their polygon bases

Question 2

prism

Answer 2

2 parallel polygons for bases and rectangular sides

prisms are named by their polygon bases

cube is a special rectangular prism made of square bases and sides

Question 2

equilateral triangle

Answer 2

a triangle whose 3 sides are the same length and whose 3 angles are the same measure (60°)

Question 3

cone

Answer 3

circular base and a curved surface and one vertex (point) (when the curved surface is spread out flat, it is similar to a triangle)

Question 3

isosceles triangle

Answer 3

a triangle with 2 sides are the same length and 2 angles are the same measure

Question 4

cylinder

Answer 4

2 parallel circular bases and a curved surface (when the curved surface is spread out flat, it is in the shape of a rectangle)

Question 4

scalene triangle

Answer 4

a triangle with no sides are the same length and no angles are the same measure

Question 5

surface area

Answer 5

the total area of all the sides of a 3-D shape

Question 5

acute angle

Answer 5

an angle less than 90 degrees (90°)

Question 6

acute triangle

Answer 6

a triangle that has angles less than 90 degrees (90°)

Question 6

right angle

Answer 6

an angle that is exactly 90 degrees (90°)

Question 7

right triangle

Answer 7

a triangle with an angle that is exactly 90 degrees (90°)

Question 8

obtuse angle

Answer 8

an angle more than 90 degrees (90°)

Question 9

obtuse triangle

Answer 9

a triangle with an angle that is more 90 degrees (90°)

Question 10

quadrilateral

Answer 10

a figure with 4 sides

Question 11

rectangle

Answer 11

a quadrilateral with 4 right angles and 2 pairs of parallel sides, opposite sides are the same length

Question 12

square

Answer 12

a rectangle whose 4 sides are the same length

Question 13

parallelogram

Answer 13

a quadrilateral with 2 pairs of parallel sides, opposite sides are the same length, two opposite angles are acute and two opposite angles are obtuse

Question 14

rhombus

Answer 14

a parallelogram whose 4 sides are the same length

Question 15

kite

Answer 15

a quadrilateral whose adjacent (side by side, sharing an angle) sides are the same length

Question 16

trapezoid

Answer 16

a quadrilateral with exactly 1 pair of parallel sides

Question 17

congruent figures

Answer 17

have the same size and shape

Question 18

similar figures

Answer 18

have the same shape, but are different sizes

Question 19

polygon

Answer 19

a closed figure formed by 3 or more lines

Question 20

polygon 3 sides

Answer 20

triangle

Question 21

polygon 4 sides

Answer 21

quadrilateral

Question 22

polygon 5 sides

Answer 22

pentagon

Question 23

polygon 6 sides

Answer 23

hexagon

Question 24

polygon 7 sides

Answer 24

heptagon

Question 25

polygon 8 sides

Answer 25

octagon

Question 26

polygon 9 sides

Answer 26

nonagon

Question 27

polygon 10 sides

Answer 27

decagon

Question 28

sum of 3 angles of a triangle

Answer 28

180°

Question 29

sum of 4 angles of a quadrilateral

Answer 29

360°

Question 30

rotation

Answer 30

spin around a fixed point full turn = 360° 1/2 turn = 180° 1/4 turn = 90° 1/3 turn = 120° 1/6 turn = 60° 1/8 turn = 45°

Question 31

translation

Answer 31

slide along a straight line

Question 32

reflection

Answer 32

flip over a line

Question 33

magnification

Answer 33

increase or decrease in size

Question 34

corresponding angles

Answer 34

angles that are in the same position in congruent or similar figures

Question 35

coordinate plane

Answer 35

formed by a horizontal line (x-axis) that intersects a vertical line (y-axis)

Question 36

coordinates (x, y)

Answer 36

the numbers in an ordered pair that describe the location of a point in the coordinate plane

Question 37

origin

Answer 37

the point where the x-axis and y-axis intersect (0, 0)

Question 38

parallel

Answer 38

lines that will never intersect

Question 39

perpendicular

Answer 39

lines that intersect at exactly 90°

Question 40

transversal

Answer 40

a line that cuts across a pair of parallel lines

Question 41

alternate angles

Answer 41

angles on opposite sides of a transversal, they are always congruent

Question 42

adjacent angles

Answer 42

side by side, have a common vertex and a common ray, if they are along a straight line, they add up to 180˚

Question 43

interior angles

Answer 43

angles that are inside the parallel lines

Question 44

exterior angles

Answer 44

angles that are outside the parallel lines

Question 45

vertical angles

Answer 45

opposite one another at the intersection of two lines, they are always congruent

Question 46

supplementary angles

Answer 46

two angles that add up to 180˚

Question 47

complementary angles

Answer 47

two angles that add up to 90˚

Question 48

perimeter

Answer 48

sum of the length of the sides

Question 49

radius

Answer 49

distance from the center of a circle to its edge (r = ½ d)

Question 50

diameter

Answer 50

distance from one side of a circle, through the center, to the other side (d = 2r)

Question 51

circumference

Answer 51

perimeter of a circle C = 2πr = πd

Question 52

area

Answer 52

the number of square units inside a polygon

Question 53

formulas for area

Answer 53

A (triangle) = ½ bh A (rectangle) = lw A (square) = s2 A (parallelogram) = bh A (trapezoid) = ½ h(b1+b2) A (circle) = πr2

Question 54

formulas for surface area

Answer 54

SA of rectangular prism = 2lw+2lh+2wh = 2(lw+lh+wh) SA of cube = 6s^2 SA of cylinder = 2πrh+2πr^2

Question 55

volume

Answer 55

amount of space enclosed in a solid (B is area of base) volume of a cylinder = πr2h volume of rectangular prism = lwh volume of prism (general) = Bh volume of pyramid (general) = 1/3 Bh volume of cone = 1/3 Bh

Question 56

Hypotenuse

Answer 56

the side of a right-angled triangle that is opposite the right angle

Question 57

Legs

Answer 57

the sides of a right-angled triangle adjacent to the right angle, they are shorter than the hypotenuse

Question 58

Pythagorean Theorem

Answer 58

a and b are legs, c is hypotenuse c^2 = a^2 + b^2

Question 59

y-intercept

Answer 59

the point where a graph crosses the y-axis

Question 60

x-intercept

Answer 60

the point where a graph crosses the x-axis

Question 61

slope intercept form

Answer 61

y = mx + b

Question 62

slope

Answer 62

the steepness of a line on a graph, rise over run

Question 63

scale factor

Answer 63

the number used to enlarge or reduce similar figures

Question 64

net

Answer 64

a two-dimensional pattern that forms a three-dimensional solid when formed