#### 4.6 Measure and calculate

##### 4.6.1 Length

This menu is enabled when a vector or a segment is selected. It generates an expression-object that
displays the vector’s or the segment’s length. You will be able to measure all kinds of lengths with
this command, if you construct the length or distance as a vector first (i.e. the distance of two
lines).

You can get the length of a vector by entering the expression ’abs(V1)’ as well, but be aware of
the fact that using the special length-command is much faster.

The most important calculations of distances are assembled in the subfolder ’Measure’ of the
macro-folder.

##### 4.6.2 Dot-product

This menu-entry is enabled if two vectors are selected. The resulting expression then displays the
dot-product (or inner product) of the two vectors. Again this command is faster than entering an
expression with ’V1*V2’.

##### 4.6.3 Enter expression

An arbitrary expression can be entered here. For a detailed description see the Chapter 15 ’Measure
and calculate’ .