Khan Academy on a Stick : Trig identities and examples

Khan Academy on a Stick

Trigonometry and precalculus

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 off-track 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)=9-8cos(18t)

More trig examples

This tutorial is a catch-all 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 triangle-side-length 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 non-right triangles that you may have thought weren't even possible!