Mammoth Memory

Trigonometry – Sin Cos Tan

 

Trigonometry – is the relationship between the sides and angles of triangles.

 

An easy way to learn about this relationship is to remember:

Sohcahtoa the great Indian war chief was very trigger happy (trigonometry) and this can help you remember trigonometry

Sohcahtoa the great Indian war chief was very trigger happy (trigonometry).

 

And then you can write down:

SOH    CAH    TOA

Pronounce          So – as in so what

                             Ca – as in cat

                           Toa – rhymes with boa (the snake)

 

In any right-angled triangle (90°), if we know:

i) The length of 2 sides

Or

ii) One side and an angle

 

We can work out the lengths and angles of all the other elements in the triangle.

The height of Nelsons column can be found using trigonometry

This allows us to find the height of statues, trees or buildings.

Trigonometry can be used to find the distance from shore to an island out at sea

This can be used to find the distances to islands.

We use one of three formulae to work this out:

`sin\ theta= (O)/H`

`cos\ theta= (A)/H`

Or

`tan\ theta= (O)/A`

SOH stands for “Sine of an angle is Opposite over Hypotenuse”.

CAH stands for “Cosine of an angle is Adjacent over Hypotenuse”.

TOA stands for “Tangent of an angle is Opposite over Adjacent”.

NOTE:

Sin, cos and tan are abbreviations of sine, cosine and tangent, while `theta`  is the symbol used for an unknown angle, and is known as theta.

`sin\ theta= (Opposite)/(Hypoten\use)`

`cos\ theta= (Adjacent)/(Hypoten\use)`

`tan\ theta= (Opposite)/(Adjacent)`

 

These formulae can only be used in a right-angled triangle as below:

These trigonometry formulas can only be used with right angled triangles

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