Midterms Flashcards
two-valued logic
every statement is either True or False
truth table
used to determine the truth or falsity of a complicated statement based on the truth or falsity of its simple components
conjunction
“and”; true when both statements are true; ^
disjunction
“or”; true when @ least 1 statement is true, V
negation
“not”, ~
inclusive “or”
doing 1/other/both
when is p → q not true?
when p is true and q is false
tautology
rule of logic
a formula which is “always true” - all the end results are true
p ⇔ q
p iff q
both p & q r equivalent. true if p & q r both true/both false
contradiction
opposite of a tautology, a formula which is “always false”
what r p &q called in p ⇒ q?
p = hypothesis
q = conclusion
p ⇒q
if p, then q
p implies q
p if q
4 ways to rewrite a statement
1) if p, then q
2) Every p has q.
3) The fact that p, implies that q
4) p iff/if/only if q
converse
q ⇒ p
inverse
~p ⇒ ~q
contrapositive
~q ⇒ ~p
Direct Argument
p ⇒ q
p
…q
premise
a statement that is assumed to be true
a given statement in an argument. the resulting statement is called the conclusion
Indirect Argument
p ⇒ q
~q
… ~p
Chain Rule
p ⇒ q
q ⇒ r
…p ⇒ r
Or Rule
p V q
~p
…q
p V q
~q
…p
good definition
built from a true conditional with a true converse
invalid argument
argument that doesn’t use rules of logic
4 rules of biconditionals
p ⇔ q
p
… q
p ⇔ q
q
… p
p ⇔ q
~p
… ~q
p ⇔ q
~q
… ~p
Venn diagram placement for conditionals/implications
two-column proof
a proof written in 2 columns
statements r listed in 1 column & justifications r listed in the other column
paragraph proof
a proof whose statements & justifications r written in paragraph form
flow proof
’s written over the arrows refer to a #-ed list of the justifications 4 the statements
a proof written as a diagram using arrows to show the connections b/w statements
postulate
a statement assumed to be true w/out proof
Addition Property of Equality
If the same # is added to equal #’s, the sums r equal
a = b → a + c = b + c
Subtraction Property of Equality
If the same # is subtracted from equal #’s the diff’s r equal
a = b → a - c = b - c
multiplication property of equality
If equal #’s r multiplied by the same #, the products r equal
a = b → ac = bc
division property of equality
if equal #’s r divided by the same nonzero #, the quotients r equal
a = b and c =/ 0 → a/c = b/c
reflexive prop of equality
a # is equal to itself
a = a
substitution property
if values r equal, 1 value may be substituted 4 the other
a = b → a may be substituted for b
distributive prop
An expression of the form a(b + c) is equivalent to ab + ac
a(b + c) = ab + ac
square root
one of 2 equal factors of a #
straight angle postulate
If the sides of an angle form a straight line, then the angle is a straight angle with a measure of 180
angle or segment addition postulate
or
whole and parts postulate
for any segment/angle, the measure of the whole is equal to the sum of the measures of its non-overlapping parts
Supplements of Angles Theorem
If 2 angles r supplementary to the same angle, then they r equal in measure
complements of angles theorem
If 2 angles r complements of the same angle, then they r equal in measure
vertical angle theorem
All vertical angles r equal in measure
corresponding angles postulate
if 2 parallel lines r intersected by a transversal, then corresponding angles r equal in measure
alternate interior angles theorem
if 2 parallel lines r intersected by a transversal, then alternate inteiror angles r equal in measure
what kinds of angles r these?
angles 3 & 6 r alternate interior angles
angles 1 & 8 r alternate exterior angles
angles 3 & 5 r cointerior angles
angles 2 & 6 r corresponding angles
co-interior angles theorem
If 2 parallel lines r intersected by a transversal, then co-interior angles r supplementary
what kinds of angles r shown below?
Angles A & D r consecutive angles
Angles A & C r opposite angles
Consecutive Angles th
If a quadrilateral is a parallelogram, then consecutive angles r supplementary
opposite angle theorem
If a quadrilateral is a parallelgoram, then opposite angles r equal in measure
Venn diagram placement for biconditionals
hypothesis
the if part of an if-then statement
conclusion
the then part of an in-then statement
implication/conditional
a statement with an if part & a then part
biconditional
the conjunction of a true conditional & its true converse, usually written using the phrase if and only if (iff)
converse of corresponding angles postulate
If 2 lines r intersected by a transversal, & corresponding angles r ocngruent, then the lines r parallel
converse of cointerior angle th
if 2 lines r cut by a transversal & cointerior angles r supplementary, then the lines r parallel
converse of alt interior angle theorem
if 2 lines r cut by a transversal & alternate interior angles r congruent, then the lines r parallel