The image you uploaded isn't fully visible or clear enough for me to extract all the necessary details to solve the problem directly. However, I can help you solve the exercise if you provide the following information:

1. The complete text of the question (Exercise 7).
2. Any given numbers or variables.
3. A description of the diagram or figure involved (if necessary).

Feel free to type out any missing parts, and I can work through the problem with you!