Answer:
The measurement which Jane finds to be 10 meters is the length of the banner.
Explanation:
The measurement of 10 meters which Jane found after measuring how long the banner is before painting is the LENGTH of the banner.
This is clear from the unit of what she finds (meters). It only indicates the measurement of one part of the banner, even though a banner has two parts, the length and width.
It is possible to find the AREA, or PERIMETER, or LENGTH.
But what she finds is the LENGTH of the banner. If it was Area or Perimeter, the unit would have been square meters.