unit 2 geometry postulates, theorems, and definitions

if a=b, then a+c=b+c

if a=b, then a-c=b-c

if a=b, then ac=bc

if a=b and c≠0, then a/c=a/b

a(b+c)=ab+ac, where a, b, and c are real numbers

if a=b, then a can be substituted for b in any equation or expression

make simpler (combining like terms)

if B is between A and C, then AB+BC=AC

if P is in the interior of ∠RST, then m∠RST=m∠RSP+m∠PST

if two angles form a linear pair, then they are supplementary

for any segment AB, (line) AB≅(line) AB

If (line) AB≅(line) CD, then (line) CD≅(line) AB

If (line) AB≅(line) CD and (line) CD≅(line) EF, then (line) AB≅(line) EF

for any angle A, ∠A≅∠A

if ∠A≅∠B, then ∠B≅∠A

if ∠A≅∠B, and ∠B≅∠C, then ∠A≅∠C

all right angles are congruent

if two angles are supplementary to the same angle (or to congruent angles), then they are congruent

if two angles are complementary to the same angle (or to congruent angles), then they are congruent

vertical angles are congruent

the sum of two angles=180º

the sum of two angles=90º

two angles opposite each other when two lines cross, these angles are equal/congruent

an angle that is 90º

the middle of a line segment, both sides of it are congruent/equal

two lines that cross each other, creating 90º angles

segments that have the same length

angles that have the same measure