Question

What is the range of the function `y = cos x`?

Answer 1

The range of a function is all possible output, or `y`, values. The range of `y=cos x` is from -1 to 1.

In interval notation, the range is [-1,1] * Note that square brackets [ ] are used because because `y=cos x` can actually equal -1 and 1 ( for example, if you plug in `x=pi`, `y=-1`).

You can see visually in a graph that `y=cos x` can only equal values between -1 and 1 on the `y`-axis, hence that it is why it is the range. The doimain, however, is all real numbers. You can see that you can plug in all sorts of `x` values, no matter how infinitely small and infinitely large they are- But you will always get a `y` value with the restriction of [-1,1]