Here is an analogy: Whenever you want to create a sentence, you'll need an alphabet. In Chemistry, If you want to build molecules, you will need atoms from different elements or the same elements. Just like alphabets make up a sentence, atoms make up molecules.
Oh Yes! With the knowledge of Trigonometry, you can know the correct slope of a roof, the proper height of a building, the rise of a stairway and many much more fun stuff like working on a video game, building different industrial machines and automobiles etc.