The SQL TAN function is a Mathematical Function that calculates the trigonometry Tangent for the specified expression. The syntax of the SQL Server TAN Function is:
-- SQL Server TAN Syntax SELECT TAN (Float_Expression) FROM [Source]
For this TAN Function demo, we use the below-shown data

SQL TAN Function Example 1
The mathematical formula for this function is TAN(x) = Length of the Opposite Side / Length of the Adjacent Side. The TAN Function calculates the Tangent value for the given angle. The following SQL Server query shows multiple ways to use the Tangent function.
DECLARE @i float SET @i = 208.45 SELECT TAN(@i)AS [SQL Tangent] -- Calculating TAN directly SELECT TAN(0.24)AS [SQL Tangent] -- Calculating TAN directly SELECT TAN(0)AS [SQL Tangent] -- Calculating TAN directly SELECT TAN(1)AS [SQL Tangent]

We used the TAN Mathematical Function to calculate the Tangent value for the variable @i. It means TAN(208.45))
SELECT TAN(@i)AS [SQL Tangent]
TAN Function Example 2
We are going to calculate the Tangent value for all the records present in [Tax Amount] and [Service Grade] using TAN Function.
SELECT [EnglishProductName] ,[SalesAmount] ,[TaxAmt] ,TAN([TaxAmt]) AS [Tax Tangent] ,[Service Grade] AS Grade ,TAN ([Service Grade]) AS [TAN Function] FROM [Mathemetical Functions]
