This is the method of calculating seasonal variation. In ratio to trend method, we will calculate annual trend values. Then on this basis, we will calculate quarterly trend value. Now, it will be easy for us to calculate the ratio of original value to trend value which will be the seasonal .
In this part of Basic Formulas of Trigonometry, we have explain the 6 functions sin, cos, tan, cosec, sec and cot. Out of three Sin, Cos, Tan are the main. These all functions are tells us the relationship between any two side of any triangle. .