# RBHS Geometry Chapter 1

### 47 terms by WillardMath Plus

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Prentice Hall California definitions and postulates

### Inductive Reasoning

A type of reasoning that reaches conclusions based on a pattern of specific examples or past events.

### Conjecture

A conclusion reached by using inductive reasoning.

### Counterexample

A particular example or instance of the statement that makes the statement false.

### Isometric Drawing

A drawing of a three-dimensional object shows a corner view of a figure.

### Orthographic Drawing

The top view, front view and right-side view of a three-dimensional figure.

### Foundation Drawing

A drawing that shows the base of a structure and the height of each part

### Net

A two-dimensional pattern that you can fold to form a three-dimensional figure.

A location.

### Space

The set of all points.

### Line

A series of points that extend in two directions without end.

### Collinear Points

Points that lay on the same line.

### Plane

A flat surface that has no thickness. Contains many lines and extends without end in the directions of its lines.

### Coplanar

Figures in the same plane.

### Postulate

An accepted statement of fact.

### Axiom

An accepted state of fact.

### Postulate 1.1 "Through any two points..."

Through any two points there is exactly one line.

### Postulate 1.2 "If two lines intersect..."

If two lines intersect, then they intersect at exactly one point.

### Postulate 1.3 "If two planes intersect..."

If two planes intersect, then they intersect in exactly one line.

### Postulate 1.4 "Through any three..."

Through any three noncollinear points there is exactly one plane.

### Segment

The part of a line consisting of two points, called endpoints and all the points between them.

### Ray

The part of a line consisting of one endpoint and all the points of the line on one side of the endpoint.

### Opposite Rays

Collinear rays with the same endpoint. They form a line.

### Parallel Lines

Lines that lie in the same plane and do not intersect.

### Skew Lines

Lines that do not lie in the same plane.

### Parallel Planes

Planes that do not intersect

### Ruler Postulate

The points of a line can be put into a one-to-one correspondence with the real numbers so that the distance between any two points is the absolute value of the difference of the corresponding numbers.

### Coordinate

The distance and direction from the origin of a number line. The coordinates of a point on a coordinate plane are in the form where x is the x-coordinate and y is the y-coordinate.

### Congruent Segments

Segments that have the same length.

If three points, A, B, and C are collinear and B is between A and C, then AB + BC = AC.

### Midpoint

A point that divides the segment into two congruent segments.

### Protractor Postulate

Let ray OA and ray OB be opposite rays in a plane. Ray OA, ray OB, and all rays with endpoint O that can be drawn on one side of line AB can be paired with the real numbers from 0 to 180 so that:
a. ray OA is paired with 0 and ray OB is paired with 180.
b. If ray OC is paired with x and ray ODis paired with y, then the measure of angle COD = |x-y|.

### Angle

Formed by two rays with the same endpoint. The rays are the sides of the angle and with the common endpoint is the vertex of the angle.

### Acute Angle

An angle whose measure is between 0 and 90

### Right Angle

An angle whose measure is 90.

### Obtuse Angle

An angle whose measure is between 90 and 180.

### Straight Angle

An angle whose measure is 180.

### Congruent Angles

Angles that have the same measure

### Vertical Angles

Two angles whose sides form two pairs of opposite rays.

Two coplanar angles that have a common side and a common vertex but no common interior points

### Complementary Angles

Two angles whose sum equals 90

### Supplementary Angles

Two angles whose sums equal 180.

### Construction

A geometric figure made with only a straightedge and a compass.

### Straightedge

A ruler with no markings on it.

### Compass

A geometric tool used to draw circles and parts of circles, called arcs.

### Perpendicular Lines

Lines that intersect and form right angles.

### Perpendicular Bisector

A line, segment, or ray that is perpendicular to the segment at its midpoint.

### Angle Bisector

A ray that divides an angle into two congruent angles.

Example: