# Sine, Cosine and Tangent

## Trignometric ratios

The ratio's between the sides of a triangle have the names Sine, Cosine and Tangent.

Sinθ= $\frac{Opposite}{Hypotenuse}$

Cosineθ = $\frac{Adjacent}{Hypotenuse}$

tangentθ =$\frac{Opposite}{Adjacent}$

These ratios are known by the calculator and so if you know any one side and an angle you can find the missing sides with a calculator.

## Acronym to memorize trig. ratios

SOH CAH TOA can be used to remember these trigonometric ratios because:

**S**ine (=) **O**pposite (over) **H**ypotenuse

**C**osine (=) **A**djacent (over) **H**ypotenuse

**T**angent (=) **O**pposite (over) **A**djacent

# Trigonometric Ratios for non-right angled triangles

## Law of Cosines:

This can be used to find the missing side of any triangle if you have two sides and the angle between them.

c2=a2+b2-2ab*Cos(C)

## Sine Rule:

This can be used if you have either:

- Any two sides and one of the angles opposite one of the sides.
- Any two angles and one side that is opposite one of those angles.

SinAa=SinBb=SinCc

# Editors

- Cerita - 659 words.
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