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# Python | sympy.expand_trig() method

• Last Updated : 18 Jun, 2019

With the help of sympy.expand_trig() method, we can expand any trigonometric expression to its lowest form.

Syntax: expand_trig(expression)

Parameters:
expression – It is the trigonometric expression which will be expanded.

Returns: Returns the trigonometric expression after its expansion.

Example #1:

In this example we can see that by using sympy.expand_trig() method, we can expand any trigonometric expression.

 `# import sympy``from` `sympy ``import` `*` ` ` `x ``=` `symbols(``'x'``)``exp ``=` `sin(``2` `*` `x) ``+` `cos(``2` `*` `x)``print``(``"Before Trigonometric Expansion : {}"``.``format``(exp)) ``   ` `# Use sympy.expand_trig() method``res_exp ``=` `expand_trig(exp) ``   ` `print``(``"After Trigonometric Expansion : {}"``.``format``(res_exp)) `

Output:

```
Before Trigonometric Expansion : sin(2*x) + cos(2*x)
After Trigonometric Expansion : 2*sin(x)*cos(x) + 2*cos(x)**2 - 1
```

Example #2:

 `# import sympy``from` `sympy ``import` `*` ` ` `x, y ``=` `symbols(``'x y'``)``exp ``=` `cos(``3` `*` `x) ``-` `sin(``3` `*` `y)``print``(``"Before Trigonometric Expansion : {}"``.``format``(exp)) ``   ` `# Use sympy.expand_trig() method``res_exp ``=` `expand_trig(exp) ``   ` `print``(``"After Trigonometric Expansion : {}"``.``format``(res_exp)) `

Output:

```
Before Trigonometric Expansion : -sin(3*y) + cos(3*x)
After Trigonometric Expansion : 4*sin(y)**3 - 3*sin(y) + 4*cos(x)**3 - 3*cos(x)
```

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