Geometry Section 2.8

theorem 2

If the non common sides of two adjacent angles form a right angle, then the angles are complementary angles

theorem 1

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

theorem 7

all right angles are congruent

reflexive property of congruent angles

angle ABC is congruent to angle ABC

theorem 4

angles complementary to the same angle or to congruent angles are congruent

theorem 3

angles supplementary to the same angle or to congruent angles are congruent

protractor postulate

given AB and a number r between 0 and 180, there is exactly one ray with endpoint A extending on either side of AB such that the measure of the angle formed is r

angle addition postulate

if R is in the interior of angle PQS, then the measure of angle PQR plus the measure of angle RQS equals the measure of angle PQS. If the measure of angle PQR plus the measure of angle RQS equals the measure of angle PQS, then R is in the interior of angle PQS

transitive property of congruent angles

if angle ABC is congruent to angle DEF and angle DEF is congruent to angle GHI, then angle ABC is congruent to angle GHI

symmetric property of congruent angles

if angle ABC is congruent to angle DEF, then angle DEF is congruent to angle ABC

theorem 9

if two angles are congruent and supplementary, then each angle is a right angle

theorem 5

if two angles are vertical angles, then they are congruent

theorem 10

if two congruent angles from a linear pair, then they are right angles

theorem 8

perpendicular lines form congruent adjacent angles

theorem 6

perpendicular lines intersect to form four right angles