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

1 Answer
Sep 24, 2014

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]

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