# Lesson 2.1 Key Terms

### 47 terms by 13ajoussef

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PLTW - IED

### Acute Triangle

a triangle whose interior angles are all acute

### Angle

the space between two lines or planes that intersect

### Area

the extent of a 2-dimensional surface enclosed within a boundary

### Axis

a straight line through a body or figure that satisfies certain conditions

### Chamfer

two surfaces meeting at an angle different from 90 degrees

### Circle

ellipse in which the two axes are of equal length

### Circumscribe

to draw a geometric figure around another figure so that the two are in contact but do not intersect

### Countersink

a hole (usually in wood) with the top part enlarged so that a screw or bolt will fit into it and lie below the surface

### Counterbore

(1) A hole consisting of two depths so that the top of the head of an inserted bolt or screw will be flush with the outside surface. (2) A bit for enlarging the upper part of a hole.

### Cylinder

a surface generated by rotating a parallel line around a fixed line

### Diameter

the length of a straight line passing through the center of a circle and connecting two points on the circumference

### Ellipse

A regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points is constant, or resulting when a cone is cut by an oblique plane which does not intersect the base.

### Extrusion

A modeling process that creates a three-dimensional form by defining a closed two-dimensional shape and a length.

### Inscribe

draw within a figure so as to touch in as many places as possible

### Mass

a body of matter without definite shape

### Origin

the point (0,0) where the x-axis and the y-axis intersect in a coordinate plane

### Parallelogram

a quadrilateral whose opposite sides are both parallel and equal in length

### Pattern

a customary way of operation or behavior

### Pi

The numerical value of the ratio of the circumference of a circle to its diameter of approximately 3.14159.

### Plane

a level of existence or development

### Polygon

a closed plane figure bounded by straight sides

### Prism

a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms

a four-sided polygon

the length of a line segment between the center and circumference of a circle or sphere

### Rectangle

a parallelogram with four right angles

### Regular Polygon

a polygon with all sides and all angles equal

### Revolution

a single complete turn (axial or orbital)

### Right Triangle

a triangle with one right angle

### Rotation

the act of rotating as if on an axis

### Round

any circular or rotating mechanism

### Solid

of definite shape and volume

### Solid Modeling

A type of 3D CAD modeling that represents the volume of an object, not just its lines and surfaces. This allows for analysis of the object's mass properties.

### Space

the unlimited expanse in which everything is located

### Square

(geometry) a plane rectangle with four equal sides and four right angles

### Surface Area

the extent of a 2-dimensional surface enclosed within a boundary

### Tap

cut a female screw thread with a tap

### Taper

the property possessed by a shape that narrows toward a point (as a wedge or cone)

### Triangle

a three-sided polygon

### Vertex

the point of intersection of lines or the point opposite the base of a figure

### Volume

physical objects consisting of a number of pages bound together

### Cartesian Coordinate System

a coordinate system for which the coordinates of a point are its distances from a set perpendicular lines that intersect at the origin of the system

### Computer-Aided Design

Software that allows you to create engineering, architectural, and scientific designs

### Geometric Constraint

Constant, non-numerical relationships between the parts of a geometric figure. Examples include parallelism, perpendicularity, and concentricity.

### Numeric Constraint

A number value, or algebraic equation that is used to control the size or location of a geometric figure.

### Obtuse Triangle

a triangle that contains an obtuse interior angle

### Three-Dimensional

Having the dimensions of height, width, and depth.

### Two-Dimensional

Having the dimensions of height and width, height and depth, or width and depth only.

Example: