with a ruler
7
You measure them.
False
you can do anything if you try
it would be a ruler
You measure it.
It is the distance between the end points
No,you cannot because a ray is something that starts from a point and goes till infinity.It is not possible to measure the length of ray.You can only measure if the ray is intersected at some point so because of the intersection the ray will be called a line segment or the intersected part and the source will be called a segment or the ray segment.You can only measure that.
You need to measure the length of each line segment or arc and then sum them.
If you travel along the length of the segment from one end to the other, whether it is curved or straight, you can measure its length. The midpoint is the spot on the segment at this mid length, equidistant from the endpoints when moving on the segment.
No as it has only one end point.
It depends on what measure you want: the angle subtended or the length of the curved segment, and also on what information you do have.