Want this question answered?
The meter.
The appropriate unit is a metre.
Meters
12*sqrt(2) ----
Metres
I would use meters.
The meter.
Metres would probably be the most convenient.
Yes
21 feet
3 feet
The appropriate unit is a metre.
With a ruler, or a measuring tape.
3 feet.
3 feet.
Please measure the length of this hallway.
A rule doesn't exist !