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Wolfram Research
Wolfram Math World: Double Angle Formulas
Part of Eric Weisstein's comprehensive math site, this page deals with double-angle formulas. This site includes traditional trigonomic double-angle functions as well as hyperbolic trigonometric function. Includes links to related terms...
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Double and Half Angle Formulas
Twenty-two problems present a variety of practice working with double-angle and half-angle formulas. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the...
Math Medics
S.o.s. Math: Double Angle and Half Angle Formulas
Double angles and half angles are explained through step by step examples. The steps are clear and easy to follow.
Oswego City School District
Regents Exam Prep: Angle Sum & Difference, Double Angle
The mathematics session examines angle sum, angle difference, double angle, and half angle formulas. The tutorial includes class notes, examples, and practice problems with solutions. The teacher resource investigates how the formulas...
CK-12 Foundation
Ck 12: Trigonometry: Double Angle Identities
[Free Registration/Login may be required to access all resource tools.] Derivation of double angle identities for sine, cosine, and tangent.
Other
Mathway: Trigonometry Formulas
Resource provides trigonometry formulas for unit circle, reciprocal identities, ratio identities, Pythagorean identities, sum and difference formulas, and double-angle formulas.
Free Math Help
Free Math Help: Double and Half Angle Formulas
Students learn about the double and half angle formulas. Definitions and formulas are included.
Windstream
Ojk's Precalculus Study Page: Double and Half Angle Formulas
This tutorial introduces the double-angle and half-angle formulas for sine, cosine, and tangent, and gives sample application and proof exercises. Assumes knowledge of the sum and difference formulas.
Other
Sierra College: Trigonometric Identities
Provides trigonometric identities, which include fundamental identities, even-odd identities, addition formulas, double-angle formulas, subtraction formulas, product-sum formulas, and identities for sin squared and cos squared.
Wolfram Research
Wolfram Math World: Trigonometric Addition Formulas
This tutorial offers formulas and explanations on trigonometric addition formulas and features an easy way to remember the sine and cosine addition formulas using matrices.
University of Saskatchewan (Canada)
University of Saskatchewan: Trigonometric Identities
The University of Saskatchewan provides an explanation of trigonometric identities, including the reciprocal identities, the addition and subtraction formulas with sine and cosine, and the double angle formulas. There are links to...
eFunda
E Funda: Multiple Angle
At this site from eFunda you can scroll to the middle of the page for a listing of multiple angle formulas for cos, sin, and tan.
Math Medics
S.o.s. Math: Trigonometry
This lesson is the main SOS Math page for trigonometry. Surf the lesson to find most any trigonometric identity, formula, and many forms of help in the area of trigonometry.
Other
Brown Math: Remembering Trig Identities
Faced with a large number of trigonometric identities, students tend to try to memorize them all. This site the emphasis is on understanding how the functions work and on memorizing only about a half dozen of them - all the others work...
Math Medics
S.o.s. Math: Table of Trigonometric Identities
This tutorial highlights the numerous trigonometric identites (but does not define the basic trigonometric functions).
Lawrence Hall of Science
The Math Page: Trigonometry: Trigonometric Identities
This resource clearly and thoroughly explains the many types of trigonometric identities. There are example problems solved, problems for the student to attempt, and answers to the student problems.
Wolfram Research
Wolfram Math World: Hyperbolic Functions
This site from MathWorld explains the hyperbolic function. The information is not too in-depth, but factual and quite a few links are provided for additional information on related subjects.