g4c8

=Grade 4 Math, Chapter 8=


 * Vocabulary**

Plane figure: A figure with only two dimensions.

Solid figure: A figure that has length, width, and height.

Cube: A solid figure with six congruent squares as its faces.

Edge: A line segment where two faces of a solid figure meet.

Face: A flat surface of a solid that does not roll.

Vertex (plural vertices): The point where two rays meet. The point where the sides of a polygon meet. The point where three or more edges of a solid figure meet.

Rectangular prism: A solid figure whose faces are all rectangles.

Triangular prism: A solid figure with two bases that are triangles and the other three faces are rectangles.

Pyramid: A solid figure whose base is a polygon and whose faces are triangles with a common vertex.

Rectangular pyramid: A solid figure with a rectangle as its base and triangles for all other faces.

Square pyramid: A solid figure with a square base and four faces that are triangles.

Sphere: A solid figure which include all points the same distance from a point.

Cylinder: A solid figure with two congruent circular bases.

cone: A solid figure with a base that is a circle and a curved surface that meets at a point.

net: A pattern used to make a solid.

polygon: A closed plane figure made up of line segments.

side: Each of the line segments of a polygon.

triangle: A polygon with three sides.

quadrilateral: A polygon with four sides.

pentagon: A polygon with five sides.

hexagon: A polygon with six sides.

octagon: A polygon with eight sides.

point: An exact location in space.

line: A straight path of points that goes on and on in two directions.

line segment: A part of a line that has two endpoints.

ray: A part of a line that has one endpoint and continues endlessly in one direction.

angle: A figure formed by two rays that have the same endpoint.

right angle: An angle that forms a square corner.

obtuse angle: An angle that is greater than a right angle.

acute angle: An angle that is smaller than a right angle.

rectangle: A quadrilateral with four right angles.

square: A quadrilateral with four right angles and all sides the same length.

trapezoid: A quadrilateral with only one pair of parallel sides.

parallelogram: A quadrilateral in which opposite sides are parallel.

rhombus: A quadrilateral in which opposite sides are parallel and all sides are the same length.

circle: A closed plane figure in which all the points are the same distance from the point called the center.

center: A point within a circle that is the same distance from all points on a circle.

radius: Any line segment that connects the center to a point on the circle.

diameter: A line segment that connects two points on a circle and passes through the center.

chord: Any line segment that connects any two points on the circle.

slide (translation): A change in the position of a figure that moves it up, down, or sideways.

flip (reflection): To turn a plane figure over.

turn (rotation): Moves a figure about a point.

congruent figures: Figures that have the same shape and the same size.

symmetric: A figure is symmetric if it can be folded into two congruent halves that fit on top of each other.

line of symmetry: A line on which a figure can be folded so that both halves are congruent.

similar figures: Figures that have the same shape and may or may not have the same size.

perimeter: The distance around a figure.

area: The number of square units needed to cover a region.

volume: The number of cubic units needed to fill a solid figure.