Oh, dude, for the length of a spider, you'd typically use millimeters or centimeters, like, depending on the size of the little critter. I mean, you could get all fancy and use micrometers if you wanna be super precise, but who has time for that, right? Just grab a ruler and eyeball it, like, it's not rocket science.
If you mean what units, that would be meters.
Use Pythagoras' theorem to find the length of the 3rd side
To measure the length of a hallway, you would typically use a measuring tool such as a tape measure or a measuring wheel. Start at one end of the hallway and extend the measuring tool to the other end, ensuring it is straight and taut for an accurate measurement. Record the measurement in the appropriate units, such as feet or meters, to determine the length of the hallway.
Milligrams, usually.
If it's a right angle triangle then the other leg will also be 13 units in length and use Pythagoras' theorem if you need to find the length of the hypotenuse.
There are no "following" units, but I would use metres.
The same units that you use for length and distance. For example, the SI unit would be the meter.
If you mean what units, that would be meters.
Meters.
It would probably be miles.
inches in customary units
You would multiply the length by the width.
Use Pythagoras' theorem to find the length of the 3rd side
If you wanted to use English Units you would want to use feet or inches. If you wanted to use the metric system you would want to use centimeters.
Volume of a rectangular block is: length*width*height. Use consistent units.
It could be if you wished to use near-obsolete measurement units.
If you are able to use fractions - or smaller units - there is never a need to do so.