## Lesson goal: Sine and cosine (sin and cos)

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The sine and cosine function (sin and cos) are easily two of the most important (and fun) functions in all of mathematics. This lesson will introduce you to their use just a bit. Most programming languages recognize sin and cos via their names. Here, sin and cos are known as sin and cos, like this:
sin(a-number) and cos(a-number)
Note that you can also use the functions math.sin and math.cos. They work the same as sin and cos. So for if you wanted to use math.sin to take the sin of $90^\circ$, you'd do math.sin(math.pi/2). For your convenience, we also have two more function defined, called dcos and dsin. These take the sine and cosine as usual, but you can put in the angle in degrees (which is convenient). So you can program dcos(90) or dsin(65) to take the cos or sin of 90, or 65 degrees.