### Instruction: How many units long is a segment whose endpoints are (2,3) and (7,15)?### Response: I need to find the length of a segment, so I can use the distance formula, which is based on the Pythagorean theorem.
The distance formula says that the distance d between two points (x_1,y_1) and (x_2,y_2) is d = sqrt((x_2 - x_1)^2 + (y_2 - y_1)^2).
In this case, I can label the point (2,3) as (x_1,y_1) and the point (7,15) as (x_2,y_2) and plug them into the formula.
So I get d = sqrt((7 - 2)^2 + (15 - 3)^2) = sqrt(25 + 144) = sqrt(169) = 13.
Therefore, the length of the segment is 13 units.