Purple Math
Purplemath: Solving Quadratic Inequalities: Concepts
Introduces a conceptual basis for solving quadratic inequalities, looking at linear inequalities and using a knowledge of what quadratic graphs look like.
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Purplemath: Solving Rational Inequalities
Demonstrates the factor-table method for solving rational inequalities.
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Purplemath: The Pythagorean Theorem
Defines the Pythagorean Theorem, and demonstrates how to use this Theorem in connection with right-angled triangles.
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Purplemath: Quadrants and Angles
Explains how to model angles in the x,y-plane, and demonstrates how to extend the concept of trig ratios to angles larger than 90 degrees.
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Purplemath: Sectors, Areas, and Arcs
Explains formulas for areas of sectors of circles and lengths of arcs. Demonstrates how to use the formulas in each of degrees and radians.
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Purplemath: Inverses of Trigonometric Ratios
You know that you can take side lengths and find trig ratios, and you know you can find trig ratios (in your calculator) for angles. What is missing is a way to go from the ratios back to the original angles. And that is what "inverse...
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Purplemath: Quartiles, Boxes, and Whiskers
Explains how to construct a simple box-and-whisker plot, and demonstrates the steps. Discusses quartiles and medians, shows how to find them, and explains how they relate to box-and-whisker plots.
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Purplemath: Using Identities to Evaluate
Demonstrates how to evaluate trigonometric functions by using trig identities.
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Purplemath: Trigonometric Identities
Lists the basic trigonometric identities, and specifies the set of trig identities to keep track of, as being the most useful ones for calculus.
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Purplemath: Ratios
Explains the basic terminology and formatting of ratios, and demonstrates how to solve typical exercises.
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Purplemath: Right Triangle Word Problems
Demonstrates how to translate, set up, and solve basic right-triangle word problems.
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Purplemath: Rounding and Significant Digits
Explains how to round to a given number of "significant digits".
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Purplemath: Solving Simple (To Medium Hard) Trig Equations
Introduces techniques for solving trigonometric equations. Provides worked examples of solving some simpler to medium-hard equations.
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Purplemath: Stem and Leaf Plots
Explains how to create a stem-and-leaf plot from a data set. Demonstrates how to format a clear stem-and-leaf plot.
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Purplemath: The Unit Circle
Relates the unit circle to the method for finding trig ratios in any of the four quadrants. Demonstrates how the unit circle might be useful.
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Purplemath: Venn Diagrams
Introduces the basic terminology of Venn diagrams, and shows how to "populate" and read Venn diagrams.
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Purplemath: Completing the Square: Deriving the Vertex Formula
This resource describes in steps how to derive the vertex formula.
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Purplemath: Conics: Circles: Introduction & Drawing
A reference site that gives definitions, examples, explanation of circle attributes and drawing circles in a coordinate plane.
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Purplemath: Factoring Quadratics: The Simple Case
This Purplemath lesson describes how to factor a trinomial. It also gives sample problems for the students to try interactively. The lesson expresses how to check the answer by multiplying through.
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Purplemath: Exponents: Scientific Notation
The lesson explains what scientific notation is, how to convert numbers into scientific and decimal notation, and gives some example problems that are worked through step by step.
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Purplemath: Graphing Linear Inequalities Lesson: Y > Mx + B, Etc.
Demonstrates, step-by-step and with illustrations, how to graph linear (two-variable) inequalities.
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Purplemath: The Midpoint Formula
This lesson from Purplemath demonstrates how to use the Midpoint Formula and shows typical problems using the Midpoint Formula.
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Purplemath: Purplemath Resources
Algebra teacher Elizabeth Staple offers answers to the question, "How do you really do this stuff?" Detailed and down-to-earth, Purplemath has dozens of graduated and cross-referenced lessons, links to other valuable resources, and...
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Purplemath: The Quadratic Formula Explained
An excellent discussion on solving quadratic formulas, accompanied by numerous examples.