De or het teenlengte?

The correct Dutch article is:

de teenlengte

Rule Words ending in -te: usually de. See the rule

How to use teenlengte

the teenlengtede teenlengte
this teenlengtedeze teenlengte
that teenlengtedie teenlengte
our teenlengteonze teenlengte
your teenlengtejouw teenlengte
every teenlengteelke teenlengte
which teenlengte?welke teenlengte?
a big teenlengte / the big teenlengteeen grote teenlengte, de grote teenlengte