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### Trigonometry Trigonometry (from Greek trigonon 'triangle' + metron 'measure' or from Sanskrit trikon 'triangle' + miti 'measurement' = trikonmiti) is a branch of mathematics that studies triangles and the relationships between their sides and the angles between the sides. Trigonometry defines the trigonometric functions, which describe those relationships and have applicability to cyclical phenomena, such as waves. The field evolved during the third century BC as a branch of geometry used extensively for astronomical studies. • ### Unit circle definition of trigonometric functions : Example: The s...

##### By: Sal Khan

Using the unit circle definition to think out the sin and cosine of a negative angle.

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Historical Epochs, With System of Mnemonics, To Facilitate the Stu...

##### By: Fitz Simon, E. A

Damanhr, Muammad ; Samarqand, Ab al-Qsim ibn Ab Bakr al-Layth, fl. 1483 ; Arabic language

• ### Historical Epochs, With System of Mnemonics, To Facilitate the Stu...

##### By: Fitz Simon, E. A.

Dambourgès, François

• ### The Teaching of Algebra (including Trigonometry): (including Trigo...

##### By: Thomas Percy Nunn

Supplemental catalog subcollection information: American Libraries Collection; Historical Literature

• ### The Teaching of Algebra (including Trigonometry): (including Trigo...

##### By: Thomas Percy Nunn

Supplemental catalog subcollection information: American Libraries Collection; Historical Literature

• ### Unit circle definition of trigonometric functions : Ferris Wheel T...

##### By: Sal Khan

Part 2 of the ferris wheel problems. Graph of h(t)=9-8cos(18t)

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Trigonometric identities : Proof: Law of Sines

##### By: Sal Khan

A simple proof of the Law of Sines

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

• ### Unit circle definition of trigonometric functions : Ferris Wheel T...

##### By: Sal Khan

Trigonometry problems dealing with the height of two people on a ferris wheen

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Basic Trigonometry

##### By: Sal Khan

Introduction to trigonometry

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Example: Trig to solve the sides and ...

##### By: Sal Khan, Monterey Institute for Technology and Education

Worked example using trigonometry to solve for the lengths of the sides of a right triangle given one of the non-right angles.

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Example: The six trig ratios

##### By: Sal Khan

Worked example where we walk through finding the major trig ratios

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Example: Using trig to solve for miss...

##### By: Sal Khan, Monterey Institute for Technology and Education

Worked example using trig ratios to solve for missing information and evaluate other trig ratios

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Unit circle definition of trigonometric functions : Example: Using...

##### By: Sal Khan, Monterey Institute for Technology and Education

Worked example using our knowledge of 30-60-90 triangles and similarity to evaluate tan, cos and sin.

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Graphs of trig functions : Determining the equation of a trigonome...

##### By: Sal Khan

Determining the amplitude and period of sine and cosine functions.

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Unit circle definition of trigonometric functions : Example: Unit ...

##### By: Sal Khan, Monterey Institute for Technology and Education

Unit circle definition to calculate sin and cos of multiple angles

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Example: Calculator to evaluate a tri...

##### By: Sal Khan, Monterey Institute for Technology and Education

Worked example showing how to use typical calculators to evaluate trigonometric functions

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Basic trigonometric ratios : Using Trig Functions

##### By: Sal Khan

Using Trigonometric functions to solve the sides of a right triangle

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Unit circle definition of trigonometric functions : Trigonometry w...

##### By: Sal Khan

The first part of a problem when the captain of a ship goes off track.

Videos and exercises on trigonometry. Watch the Geometry playlist first if you have trouble understanding the topics covered here.

• ### Trigonometric identities : Trig identies part 3 (part 5 if you wat...

##### By: Sal Khan

Continuation of the playing around with trig 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

• ### Trigonometric identities : Law of cosines

##### By: Sal Khan

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

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 