Theorems
Angles
Formulas
Vocabulary
Axioms and Common Notions
100

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

Theorem 1-2 Congruent Supplements Theorem

100

90° angle, created at the intersection of two perpendicular straight lines

Right angle


100


Midpoint formula

100

a location and has no size

A point
100

Can draw a straight line using a straight edge

Axiom #1

200

If a transversal intersects two parallel lines, then corresponding angles are congruent.

Theorem 2-2 Corresponding Angles Theorem
200

Two angles that, when added together, form 180°

Supplementary angles

200

(x,y) > (y, -x)

Rotation of 90° clockwise

200

bisects all sides at 90°

Circumcenter

200

Things that are congruent are equal to one another

Common Notion #4

300

If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

Theorem 4-1 Isosceles Triangle Theorem and the Converse

300

Two angles that, when added together, form 90°

Complementary angles
300

(x, y) > (-x, -y)

Rotation of 180° clockwise and counterclockwise

300

equal, but may be off by a decimal

Congruent

300

All right angles are congruent

Axiom #4

400

If the hypotenuse and one leg of a right triangle are congruent to the hypotenuse and leg of another right triangle, then the triangles are congruent. 

Theorem 4-8 Hypotenuse Leg Theorem

400

If a transversal intersects two parallel lines, then ________ are congruent. 

Corresponding angles

400

(x, y) > (-y, x) 

Rotation of 270° clockwise

400

formed by two rays with the same endpoint

angle

400

If A = B and B = C, then A = C (Transitive Property) 

Common notion #1

500

If a point is on the bisector of an angle, then the point is equidistant from the sides of the angle.

Theorem 5-4 Angle Bisector Theorem

500

Each of the pairs of opposite angles made by two intersecting lines.

Vertical angles

500

a2 + b2 = c2

Pythagorean Theorem

500

bisecting angles

Incenter

500

The whole is greater than its part

Common notion #5