Selecting 3 sides of a rectangle

This is my first post and I am new to CAD in general, as well as LibreCAD.  I try to follow a YouTube tutorial on how to make a title block. I already got stuck quite early. In the video it shows that 3 sides of a rectangle are being selected. It is however unclear to me how this is done. It looks like a setting is missing. Can someone help me?

Welcome WhiskyGolf!

Probably the video uses another version of LibreCAD or the author did not explain all the steps.

So it helps to provide more information, e.g. a link to the video in question, your LibreCAD version (Help-About) and maybe operating system.

A guess is, that the video shows a rectangle built from single line entities and your rectangle is a polyline.
The polyline is an entity container and you can select only the whole container, not a single line or arc.
Use Explode from Modify tool menu to explode the rectangle, then each side can be selected separately.

Armin

The remark about Explode did the trick. The video was:https://www.youtube.com/watch?v=SDKQfkmo7hU
and the LibreCAD version I use is:
Version: 2.2.0.2
Compiler: GNU GCC 13.1.0
Compiled on: Jul 29 2023
Qt Version: 5.12.11
Boost Version: 1.75.0
System: Windows 10 (10.0)

Thanks for the quick response.

 We want to maximize the area of the rectangle implied by choosing the length of three of its sides, with the condition that the three chosenIn a rectangle,
 slope unblocked   you'll add up the two longer sides and the two shorter sides, or double the length and add it to double the width (P = 2l + 2w). Circle: To measure the distance around a circle, or its perimeter, you use the perimeter formula two times pi times the radius (P = 2πr).