Mastering the Formal Geometry Proof
Suppose you need to solve a crime mystery. You survey the crime scene, gather the facts, and write them down in your memo pad. To solve the crime, you take the known facts and, step by step, show who committed [more…]
Sizing Up the Area of a Polygon
Not only can polygons be classified by the number of sides they have and by their angles, but they can also be grouped according to some of their qualities. Polygons can have three personality characteristics [more…]
Simple and Easy Geometry Tips and Tools
The first rule of life? Life (as well as geometry) can be difficult. But why make it more difficult than it has to be? Do you need help with geometry? Here are 11 tried-and-true tips to make your forays [more…]
Measuring and Making Angles
On a map, you trace your route and come to a fork in the road. Two diverging roads split from a common point and form an angle. The point at which the roads diverge is the [more…]
Classifying Three Types of Triangles
Triangles are classified according to the length of their sides or the measure of their angles. These classifications come in threes, just like the sides and angles themselves. That is, a triangle has [more…]
Defining the Radian in Trigonometry
A person's introduction to angles is usually in terms of degrees. You probably have a good idea of what a 45-degree angle looks like. And even most middle-school students know that a triangle consists [more…]
Discovering Pythagorean Triples
The Pythagorean Theorem is certainly one of the most famous theorems in all of mathematics. Mathematicians and lay people alike have studied it for centuries, and people have proved it in many different [more…]
Geometry Formulas for Polygons
Polygons, those many-sided objects so popular in geometry circles, are subject to their own formulas that help you find the area and angles of various geometrical shapes. Have a look at the most common [more…]
Coordinate Geometry Formulas
When you work in geometry, you sometimes work with graphs, which means you’re working with coordinate geometry.Becoming familiar with the formulas and principles of geometric graphs makes sense, and you [more…]
Geometry Symbols
If you’re studying geometry, you’re seeing symbols everywhere — symbols for arcs and angles, lines and triangles as well as symbols for the relationships between lines and angles and so on. Following is [more…]
Triangle Terminology for Geometry
Triangles are at least a third of geometry (tri = three . . . a little geometry humor). But, seriously, the sides and angles of triangles may have all sorts of relationships to each other, and the following [more…]
Geometry Formulas for 3-D Objects
You know those big, 3-D movie blockbusters? They’d be nowhere without geometry . . . geometry and those weird glasses. Knowing the formulas for 3-D objects is key in the real world of geometry, and those [more…]
Geometry Formulas and Rules for Triangles
The three-angled, two-dimensional pyramids known as triangles are one of the building blocks of geometry (however three-cornered they may be). Triangles, of course, have their own formulas for finding [more…]
Geometry Formulas and Theorems for Circles
Geometry isn't all about pointy angles — there are circles, too. What’s interesting about circles isn’t just their roundness: Become familiar with geometry formulas that help you measure angles around [more…]
Geometry Workbook For Dummies Cheat Sheet
The helpful geometry symbols, formulas, and principles in this cheat sheet ease your learning curve. Working with geometry means never being bored: You get to work with lines, angles, and arcs; triangles [more…]
Hit List of Geometry Formulas
These important formulas, theorems, and properties are vital to studying geometry. If you're working on a geometry problem and get stumped, go through these formulas and make sure you've applied them correctly [more…]
Common Geometry Symbols
Using geometry symbols will save time and space when writing proofs, properties, and figuring formulas. The most commonly used geometry symbols and their meanings are [more…]
Proof Strategies in Geometry
Knowing how to write two-column geometry proofs provides a solid basis for working with theorems. Practicing these strategies will help you write geometry proofs easily in no time: [more…]
Geometry For Dummies Cheat Sheet
Successfully understanding and studying geometry involves using strategies for your geometry proofs; knowing important equations; and being able to identify commonly used geometry symbols. [more…]
Special Right Triangles for Trigonometry
Trigonometry is focused on studying triangles, and some right triangles are special even in trig. The following figures show the 30-60-90 triangle and the Isosceles triangle for your trigonometry enjoyment [more…]
Right Triangle Definitions for Trigonometry Functions
Defining the hypotenuse and the adjacent and opposite sides of triangles is what trigonometry is all about. But trig has a set of definitions for right triangles, which are shown with the following figure [more…]
Trigonometry Functions for Acute Angles
Trigonometry deals with triangles, which necessarily means dealing with acute angles — those 90 degrees or less. The following table shows the exact sine, cosine, and tangent functions for select acute [more…]
Degree/Radian Equivalences for Trigonometry
Radians, as units of plane angles, can be translated into degrees. If you’re using trigonometry, knowing those equivalences comes in very handy. The following table shows select equivalences: [more…]
Coordinate Definitions for Trigonometry Functions
In trigonometry, you can get up to all sorts of plots — as long as you’re plotting triangles. The coordinate definitions for each of the trig functions are shown in the following list: [more…]
Signs of Trigonometry Functions in Quadrants
When you plot triangles in trigonometry, trig functions have different signs, depending on the quadrant they’re in. In quadrant I, for example, all functions are positive. The following figure shows which [more…]
