Let's say you've got a bullet lodged into a wall. It's in there at a certain angle. Now imagine that this bullet came from a sniper's rifle. By measuring the height of surrounding buildings, the elevation of the bullet on the wall, and distances to and from possible roof levels of other buildings, you can use Trigonometry to figure out where the sniper was.

Or you can rotate a sine function with bounds from limit "a" to limit "b," rotate it around an axis, and get a volume for a sine-shaped random volume.

Sin and Cos are also used heavily in Physics formulas in order to generate numbers necessary to do... stuff.

Or you can say cosine looks like a flower pot.