Final answer:
The length of the line segment is 7 units.
Step-by-step explanation:
The length of a line segment is calculated using the distance formula. The distance formula is represented as follows:
d = sqrt((x2 - x1)^2 + (y2 - y1)^2)
In this case, the coordinates of the endpoints are (1,2) and (1,9). Plugging these values into the formula, we get:
d = sqrt((1 - 1)^2 + (9 - 2)^2)
d = sqrt(0 + 49)
d = sqrt(49)
d = 7
The question is asking for the length of a line segment with specific endpoints in a two-dimensional space. Since both endpoints have the same x-coordinate (1), the line segment is vertical. The length of the line segment can be found by calculating the difference between the y-coordinates of the endpoints (9 and 2), which gives us a length of 7 units.
Therefore, the length of the line segment is 7 units.