## Task 4

A segment $AB$ has a length $AB=12 \mathrm{~cm}$. On $AB$ lie the points $C$ and $D$. The length $AD=9$ $\mathrm{cm}$ and the length $CB=7 \mathrm{~cm}$. Draw. Determine the length of the segment $CD$.
$C D=4 \mathrm{~cm}$

![](https://cdn.mathpix.com/cropped/2024_06_06_b85a894aa8dbf722a7b3g-2479.jpg?height=91&width=920&top_left_y=800&top_left_x=471)

### 13.6.2 2. Round 1977, Class 4