Now that we have our shapes outlined, we can start defining our whole sketch. Follow these steps to do so:

1. We can define the sketch by adding the dimensions and relations shown in the following diagram. Note that, when defining one line, the mirrored line will also be defined in the same way (20 mm). Also, note that we can add dimensions between the mirrored entities (50 mm). After adding those dimensions, we will notice that it becomes fully defined:

In this exercise, we defined the whole sketch after applying the mirror. An alternative approach is to fully define the first triangle before using the Mirror Entities command. In this scenario, the mirrored triangle will also be fully defined, directly after mirroring. 

The Copy option in mirroring is used if we wish to keep the original shape. If the Copy option is checked, we will keep the original shape and create a mirrored shape. If it is unchecked, the original shape will be deleted and we'll be left with the mirrored shape only.

This concludes the Mirror Entities sketching command. Note that, in practice, whichever order we outline and define our sketches in can vary. As you gain more experience with sketching, you will have your own approach for doing things. Now, we can start learning about the Offset Entities sketch command.