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:

Sine (=) Opposite (over) Hypotenuse 

Cosine (=) Adjacent (over) Hypotenuse

Tangent (=) Opposite (over) Adjacent

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

View count: 4708