# TrigCombine Command

From GeoGebra Manual

- TrigCombine( <Expression> )
- Transforms a trigonometric expression including products of trigonometric functions into an expression without products involving sums of variables.
**Examples:**`TrigCombine(sin(x) cos(3x))`

gives {\frac{1}{2} sin \left( 4 x \right) - \frac{1}{2} sin \left( 2 x \right)}`TrigCombine(sin(x) + cos(x))`

gives {\sqrt{2} cos \left( x - \frac{1}{4} \pi \right)} .

- TrigCombine( <Expression>, <Target Function> )
- Transforms a trigonometric expression including products of trigonometric functions into an expression without products involving sums of variables, preferring the given target function.
**Example:**`TrigCombine(sin(x) + cos(x), sin(x))`

gives {\sqrt{2} sin \left( x + \frac{1}{4} \pi \right)} .

**Notes:**

- In the CAS View undefined variables can be used as well.
**Example:**`TrigCombine(sin(p) cos(3p))`

gives {\frac{1}{2} sin \left( 4 p \right) - \frac{1}{2} sin \left( 2 p \right)}.

- See also TrigExpand Command and TrigSimplify Command.