# Geometry Unit 1

always

Two points lie in exactly one line.

sometimes

Three points lie in exactly one line.

never

Three collinear points lie in exactly one plane.

never

Two interescting planes intersect in a segment.

sometimes

Three points determine a plane.

always

Two intersecting lines determine a plane.

sometimes

Two non-intersecting lines determine a plane.

always

Three points are _____ coplanar.

line

Through any two points there is exactly one____

plane

Through any three non-collinear points, there is exactly one____

line

If two points lie in a plane, then the____containing these two points lie entierely in the plane.

point

If two lines intersect, then their intersection is exactly one___

plane

Given a line and a point that is NOT on that line, there is exactly one___which contains both the point and the line

plane

If two lines intersect, there is exactly one___which contains the two lines.

false

A given triangle can lie in more than one plane

true

any two points are collinear

false

two planes can intersect in only one point

false

two lines can intersect in two points

ruler postulate

points of a line can be put into a one-to-one correspondence with the set of real numbers so that no two points are paired with the same coordinate.

segment addition postulate (definition of between)

If R is between S and I, then SR + RI = SI

congruent segments

segments that are equal in length

segment bisector

a segment, line or ray that intersects a segment at its midpoint

midpoint

a point that divides a segment into 2 congruent segments

ray

set of points with one endpoint continuing in one direction forever

opposite rays

2 rays that have the same endpoint and go in opposite directions to form a line.

probability

the # of favorable outcomes over the total # of possible outcomes (desired length over whole length)

intuition

conclusion is based on insight

induction

conclusion is reached from past observations

deduction

conclusion is drawn logically from given information (facts)/accepted truths

conditional statement

a statement that can be written in if, then form. (if p then q)

hypothesis

this is the part of the sentence that follows the word "If...

conclusion

this is the part of the sentence that follows the word "then...

converse

q--->p

inverse

~p--->~q, is formed by negating the hypothesis and negating the conclusion of the original statement.

contrapositive

~q--->~p, is formed by negating both the hypothesis and the conclusion, and then interchanging the resulting negations. (It does both jobs on the INVERSE and the CONVERSE)