Formal proofs present the oh-so-mathematical evidence in two columns: one for the statement they are claiming is true, and the other for the reasoning behind them.

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Characteristics of Parallelograms

Cosines

Transformations

Vertical Angle Theorem

Introduction to 3D Geometry

Slopes of Parallel and Perpendicular Lines

Similar Figures

Polygons

Perimeter and Circumference

Surface Area of Cylinders

Angles of a Polygon

Triangle Inequality Theorem

Collinearity

SOHCAHTOA

SSS Postulate

Volumes of Pyramids and Cones

Sines

Volumen de un Cubo

Converting Between Degrees and Radians

Attributes of Circles

Proving Lines are Perpendicular

The Tangent Function

Perimeter of a Rectangle

Area Formulas

Area of an Irregular Shape

Cubes: Surface Area and Volume

Triangles

Proving Lines are Parallel

Geometric Word Problems

Rhombi

Equations of Circles

Verifying Trig Identities

A Midsummer Night's Dream

Lines, Segments and Rays

Law of Sines

Exterior and Remote Interior Angles

Surface Area of a Cube

Constructions

Tangent Half-Angle Formula

Coordinate Geometry

Finding the Distance Between Two Points

SAS, ASA, AAS

Law of Cosines

Midsegment Theorem

Centers of a Triangle

Parallel Lines and Transversals

Complementary and Supplementary Angles

Translations and Functions

Solving Trigonometric Equations

ACT Math 2.2 Coordinate Geometry

Volume

Secant Angles

Special Right Triangles

Area of a Sector

Area

Inscribed Angles

Perimeter of Irregular Shapes

30-60-90 Triangle

Linear Pairs

Volumes of Prisms and Cylinders

Proving Triangles Congruent 2

Transformaciones

Coordinates and Distance Formula

Properties of Equality and Congruence

Proving Triangles Congruent

Angles