Can minutes be used to measure the length?

Question

I am using an Old American maths textbook and it uses US customary units. For the length, they use minutes (like $6'$ for the altitude of a triangle). How is this related to foot which is the unit of length in US customary units? This seems a bit strange to me.

Answer 1

In the old Imperial measures, still used in the US, ' means feet and '' means inches (12 inches to the foot).

Answer 2

$6'$ as a length would mean $6$ feet.

A minute is usually a measure of time ($1/60$th of an hour) but can also be a measure of angle ($1/60$th of a degree). As an angle $6$ minutes would also be written $6'$, but it doesn't uniquely specify a length.