If 2 angles are rt angles, then congruent

Theorem 2

If 2 angles are straight angles, then congruent

Theorem 3

If a conditional statement is true, then the contrapositive of the statement is also true

Theorem 4

If angles are supp. to the same angle, then congruent

Theorem 5

If angles are supp. to congruent angles then congruent

Theorem 6

If angles are comp. to the same angle, then congruent

Theorem 7

If angles are complementary to congruent angles, then congruent

Theorem 8 (Addition Property)

If a seg. is added to 2 congruent segs., the sums are congruent

Theorem 9 (Addition Property)

If an angle us added to 2 congruent angles, the sums are congruent.

Theorem 10 (Addition Property)

If congruent segs. are added to congruent segs., the sums are congruent

Theorem 11 (Addition Property)

If congruent angles are added to congruent angles, the sums are congruent

Theorem 12 (Subtraction Property)

If a seg or angle is subtracted from congruent segs or angles, the differences are congruent

Theorem 13 (Subtraction Property)

If congruent segs or angles are subtracted from congruent segs or angles, the differences are congruent

Theorem 14 (Multiplication Property)

If segs or angles are congruent, their like multiples are congruent

Theorem 15 (Division Property)

If segs or angles are congruent, their like divisions are congruent

Theorem 16 (Transitive Property)

If angles or segs are congruent to the same angle or seg., they are congruent to each other

Theorem 17

If angles or segs., are congruent to congruent angles or segs., they are congruent to each other

Theorem 18

Vertical angles are congruent

Theorem 19

All radii of a circle are congruent

Theorem 20

If 2 sides of a triangle are congruent, the angles opp. the sides are congruent

Theorem 21

If 2 angles of a tri. are congruent, the sides opp. the angles are congruent

Theorem 22

Midpoint formula: X1+X2/2, Y1+Y2/2

Theorem 23

If 2 angles are both supp. and congruent, then they are rt angles

Theorem 24

If 2 pts. are each = dist. from the endpoints of a set, then the 2 pts. det. the perpendicular bis of that seg

Theorem 25

If a pt. is on the perpendicular bis of a seg, then it is = dist. from the endpoints of that seg.

Theorem 26

If 2 non vertical lines are II, then their slopes are equal

Theorem 27

If the slopes of 2 non vertical lines are equal, the the lines are II

Theorem 28

If 2 lines are perpendicular and neither is vertical, each line's slope is the opp. reciprocal of the others

Theorem 29

If a line's slope is the opp. reciprocal of another line's slope, the 2 lines are perpendicular

Theorem 30

The measure of an ext. angle of a tri is greater than the measure of either remote int. angle

Theorem 31

Alt. Int. Angles congruent to II lines

Theorem 32

Alt. Ext. Angela congruent to II lines

Corr. Angles congruent to II lines

...

Theorem 34

If 2 lines are cut by a transversal such that 2 int. Angles on the same side of the transversal are supp., the lines are II

Theorem 35

If 2 lines are cut by a transversal such that 2 ext. angles on the same side of the transversal are supp., the lines are II

Theorem 36

If 2 cop. lines are perpendicular to a third line, they are II

Theorem 37

II lines then alt. Int. Angles are congruent

Theorem 38

If 2 II likes are cut by a trans, then any pair of angles formed are either congruent or supp.

Theorem 39

II lines then alt. Ext. angles congruent

Theorem 40

II lines are corr. Angles are congruent

Theorem 41

If 2 II lines are cut by a trans., each pair of int. Angles on the same side of the trans are supp.

Theorem 42

If 2 II lines are cut by a transversal, each pair of ext. angles on the same side of the trans. are supp.

Theorem 43

In a plane, of a line is perpendicular to one of two II lines, it is perpendicular to the other

Theorem 44 (Transitive Property of II Lines)

If 2 lines are II to a third line, they are II to each other