705K views · 5.2K reactions | One of the most fascinating things...

48M views · 7K reactions | Skill or form of art? This Thai vendor creating instant ice cream rolls was one of Storyful's most watched videos this week: https://www.youtube.com/watch?v=Ybb57frsdKk | storyful | Facebook

The sine function is one of the most important ideas in trigonometry. It comes from studying right triangles, where sine is the ratio of the side opposite an angle to the hypotenuse. More broadly, sine describes patterns of oscillation, rotation, and wave motion. Its graph is a smooth, repeating curve that goes up and down between –1 and 1, repeating every 360 degrees. Because of this, sine shows up in physics to model things like sound waves, vibrations, and circular motion. The cosine function