Khan Academy on a Stick
Trig identities and examples

Trigonometry Identity Review/Fun
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Trigonometric Identities
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Introduction to trigonometric identities
 Examples using Pythagorean identities to simplify trigonometric expressions

Proof: sin(a+b) = (cos a)(sin b) + (sin a)(cos b)
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Proof of the trig identity sin(a+b) = (cos a)(sin b) + (sin a)(cos b)

Proof: cos(a+b) = (cos a)(cos b)(sin a)(sin b)
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Proof of the trig identity: cos(a+b) = (cos a)(cos b)(sin a)(sin b)

Trig identities part 2 (part 4 if you watch the proofs)
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More playing around with trig identities

Trig identies part 3 (part 5 if you watch the proofs)
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Continuation of the playing around with trig identities
 Cosine addition identity example
 Double angle formula for cosine example
Trigonometric identities
If you're starting to sense that there may be more to trig functions than meet the eye, you are sensing right. In this tutorial you'll discover exciting and beautiful and elegant and hilarious relationships between our favorite trig functions (and maybe a few that we don't particularly like). Warning: Many of these videos are the old, rougher Sal with the cheap equipment!

Navigation Word Problem
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Trigonometry problem involving two ships colliding.

Fun Trig Problem
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A trig problem involving the quadratic equation.

IIT JEE Trigonometry Problem 1
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2010 IIT JEE Paper I #29 Trigonometry problem

IIT JEE Trigonometric Maximum
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2010 IIT JEE Paper 1 Problem 48 Trigonometric Maximum

IIT JEE Trigonometric Constraints
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2010 IIT JEE Paper 1 Problem 47 Trigonometric Constraints

Trigonometric System Example
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2010 IIT JEE Paper 1 Problem 55 Trigonometric System

2003 AIME II Problem 11
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A little trigonometry to figure out the area of a triangle

2003 AIME II Problem 14
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Trigonometry and geometry to find the area of an equilateral (but not regular) hexagon

Trigonometry word problems (part 1)
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The first part of a problem when the captain of a ship goes off track.

Trigonometry word problems (part 2)
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The second part of the problem of the offtrack ship captain

Ferris Wheel Trig Problem
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Trigonometry problems dealing with the height of two people on a ferris wheen

Ferris Wheel Trig Problem (part 2)
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Part 2 of the ferris wheel problems. Graph of h(t)=98cos(18t)
More trig examples
This tutorial is a catchall for a bunch of things that we haven't been able (for lack of time or ability) to categorize into other tutorials :(

Law of cosines example
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Proof of the law of cosines
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Proof of the law of cosines to solve for a side of a triangle when 2 sides and an angle are known.

Proof: Law of Sines
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A simple proof of the Law of Sines
Law of cosines and law of sines
The primary tool that we've had to find the length of a side of a triangle given the other two sides has been the Pythagorean theorem, but that only applies to right triangles. In this tutorial, we'll extend this trianglesidelength toolkit with the law of cosines and the law of sines. Using these tool, given information about side lengths and angles, we can figure out things about even nonright triangles that you may have thought weren't even possible!