When the external form of a lake is measured, what is really calculated is it’s .

The length of a lake is measured as the longest straight-line shoreline-to-shoreline distance across a lake. ... Another important measurement is lake width (“W” in Figure 1), taken as the longest shoreline-to-shoreline measurement at right angles to the length.

Explanation:

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.