# TrigExpand Command

From GeoGebra Manual

This page is about a feature that is supported only in GeoGebra 4.2. |

This command works in CAS View only.

- TrigExpand[ <Expression> ]
- Transformes a trigonometric expression into an expression using only simple variables as arguments.
**Example:**`TrigExpand[tan(x+y)]`

gives \frac{cos(x) sin(y) + cos(y) sin(x)}{cos(x) cos(y) - sin(x) sin(y)}.

- TrigExpand[ <Expression>, <Target Function> ]
- Transformes a trigonometric expression into an expression using only simple variables as arguments, preferring the given target function.
**Example:**`TrigExpand[tan(x+y),tan(x)]`

gives \frac{-tan(x) - tan(y)}{tan(x) tan(y) - 1}.

- TrigExpand[ <Expression>, <Target Function>, <Target Variable> ]
- Transformes a trigonometric expression into an expression using only simple variables as arguments, preferring the given target function and tagret variable.
**Example:**`TrigExpand[sin(x),sin(x),x/2]`

gives 2cos(\frac{x}{2})sin(\frac{x}{2}).

- TrigExpand[ <Expression>, <Target Function>, <Target Variable>, <Target Variable> ]
- Transformes a trigonometric expression into an expression using only simple variables as arguments, preferring the given target function and target variables.
**Example:**`TrigExpand[csc(x) - cot(x) + csc(y) - cot(y), tan(x), x/2, y/2]`

gives tan(\frac{x}{2})+tan(\frac{y}{2}).

**Note:**See also TrigSimplify Command and TrigCombine Command.