Plane figure A two dimensional figure. Chapter 10
polygon A closed plane figure of 3 or more line segments. They can have a different number of sides and angles. Chapter 10
triangle A 3 sided polygon with 3 angles. Chapter 10
quadrilateral A 4 sided polygon with 4 angles. Chapter 10
pentagon A 5 sided polygon with 5 angles. Chapter 10
hexagon A 6 sided polygon with 6 angles. Chapter 10
octagon An 8 sided polygon with 8 angles. Chapter 10
perimeter The distance around the outside of an object or shape. Chapter 10
area The number of square units needed to cover a plane figure without overlapping. Chapter 10
equilateral triangle A triangle with 3 equal sides. Chapter 10
isosceles triangle A triangle with 2 equal sides. Chapter 10
scalene triangle A triangle with NO equal sides. Chapter 10
right triangle A triangle with one right angle. Chapter 10
obtuse angle Angle bigger than 90 Chapter 10
acute angle Angle smaller than 90 Chapter 10
parallel Lines that are the same distance apart. Parallel lines do not meet. Chapter 10
rectangle Opposite sides are same length and are parallel. It also has 4 right angles. Chapter 10
rectangular solid A 3-dimensional figure with six faces that are rectangles. Chapter 10
square 4 sided that are the same length, opposite sides are parallel, has 4 right angles. Chapter 10
parallelogram Opposite sides are the same length and are parallel. Chapter 10
cube A 3-dimensional figure with 6 congruent square faces. Chapter 10
cone 3-dimensional figure with a curved surface and a circular base which comes to a point called the vertex. Chapter 10
pyramid A 3-dimensional figure with 5 faces. Chapter 10
cylinder A 3-dimensional figure having two circular bases and a curved surface connecting the two bases. Chapter 10
sphere A 3-dimensional figure that has the shape of a round ball. Chapter 10
volume The number of cubic units needed to fill a 3-dimensional figure or solid figure. Chapter 10
cubic unit A unit for measuring volume, such as a cubic inch or a cubic centimeter. Chapter 10