Let’s understand it using an example.
Find value of tan28036/
Use the natural tangent table for this.
Step 1: first locate the 28˚ in first degrees column.
Step2: then, locate 36َ in next columns ranging from 0/ to 54/.
The coinciding point will give you the value of tan28036/ which is 0.5452.
Find the value of tan72028/
As there is no column of 28/
We first find the value of tan72028/ and then add the mean difference of 4/.
i.e. value of tan72028/ (follow above steps)
Now, add 4/ value from mean difference column in 72˚ row i.e. 129.
The answer will be 3.1524 + 129 = 3.1653
In the similar way you can find the value of sine and cosine using natural sine and natural cosine tables.
Hope, this method is clear to you.