<em>A solid is a sample of matter that retains its shape and density when not confined, A liquid is a sample of matter that conforms to the shape of a container in which it is held, and which acquires a defined surface in the presence of gravity.</em>
I hope this gives you some sort of assistance.
Reread the textbook just to make it better <em>(if you can quickly look through it)</em>
Because these are all congruent, and they're all vertical angles, this would show you that what ever you would do to one side, you do also to the other side.