Taking the trigonometrically study, there is a need to take the right angled triangle into consideration because all the calculations of trigonometry are derived from this only. Like, in a right angled triangle, the largest side is called the hypotenuse, the base is the smallest of all, which is also called the adjacent side and then comes the opposite side. The three most primary trigonometrically formulae can be derived from the same like Sin A or SOH which is having the formula Opposite divided by Hypotenuse, mathematically it can be expressed as Sine or SOH= Opposite/ Hypotenuse.

Secondly Cosine or CAH= Adjacent/Hypotenuse.

Thirdly, Tan or TOA=Opposite/Adjacent.

Since these three are the most important functions in trigonometry. They are expressed as SinF, CosF and TanF. The calculation is based on a very simple understanding like there is one side of the right angled triangle which is divided by another side, there is just a need to know which are these side, as the largest side is hypotenuse, and the smallest of them is the base and the remaining is the opposite which is opposite to the base. The saying "sohcahtoa" helps us to learn the remaining details and formulae of trigonometry.

Example: what are the sine, cosine and tangent of 60°?

Now we know the lengths, we can calculate the functions:

Sine

soh...

Sin (30°) = 12 = 0.5

Cosine

...cah...

Cos (30°) = 1.732...2 = 0.866...

Tangent

...toa

Tan (30°) = 11.732... = 0.577...

Similarly, there are other formulae which can be obtained from this also.