# Chapter 1 defenitions

## 37 terms

### conjecture

a conclusion you reach using inductive reasoning

### inductive reasoning

reasoning based on patterns that you observe

### counterexample

an example to prove the conjecture incorrect

### isometric drawing

a 3d drawing that shows three sides of a figure from a corner view

### orthographic drawing

another way to show a 3d drawing, it shows a top, front, and right side view

### foundation drawing

shows the base structure and the height of each part

### net

a 2d pattern that you can fold to form a 3d figure

a location

### space

the set of all points

### line

a series of points that extends in two opposite directions without end

### collinear points

points that lie on the same line

### plane

a flat surface that has no thickness

### coplanar

points and lines that are in the same plane

### postulate

an accepted statement of fact

### segment

the part of a line consisting of two endpoints

### ray

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

### opposite rays

two collinear rays with the same endpoint

### parallel lines

coplanar lines that do not intersect

### skew lines

noncoplanar lines that do not intersect nor are parallel

### parallel planes

planes that do not intersect

### congruent segments

two segments with the same length

### midpoint

a segment of a point that divides the segment into two congruent segments

### angle

formed by two rays with the same endpoint

### congruent angles

angles with the same measure

### acute angle

an angle between the measurement of 0-90 degrees

### right angle

an angle with a measurement of 90 degrees

### obtuse angle

an angle between the measurement of 90-180 degrees

### straight angle

an angle with the measurement of 180 degrees

### vertical angles

two angles whose sides are opposite rays

### adjacent angles

two coplanar angles with a common side, common vertex, and no common interior points

### complementary angles

two angles whose measures have sum of 90 degrees

### supplementary angles

two angles whose measures have a sum of 180 degrees

### construction

when you use a straightedge and a compass to draw a geometric figure

### straightedge

a ruler with no markings on it

### compass

a geometric tool used to draw circles and parts of circles called arcs

### perpendicular lines

two lines that intersect to form right angles

### perpendicular bisector

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