Answer
12
Explanation
The length of a segment with endpoints (x₁, y₁) and (x₂, y₂) is calculated as follows:
![length=√((x_2-x_1)^2+(y_2-y_1)^2)](https://img.qammunity.org/2023/formulas/mathematics/college/cnb74693pb64d8648akl9at73e0sqdv4g3.png)
In this case, the endpoints are C(0,3) and D(0,7), then the length of the segment CD is:
![\begin{gathered} \bar{CD}=√((0-0)^2+(7-3)^2) \\ \bar{CD}=√(4^2) \\ \bar{CD}=4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/mcs9tzjv0qu0lllde4ilmdnsus133x2v8h.png)
After CD is dilated by a factor of 3, the length of the image will be:
![\begin{gathered} \text{ length of the image of CD = }3*\text{ length of CD} \\ \text{ length of the image of CD = }3*4 \\ \text{ length of the image of CD = 12} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/cej5wwflfcul8ikoszh6xrxzeyydqantyx.png)