What is the range of a cosine function? a. irrational numbers c. positive numbers b. negative numbers d. all real numbers between -1 and 1 including -1 and 1

The smallest y can be is y = -1. The largest it can be is y = 1. The value of y can be anything in between. The value of y is a real number.

Choice D) All real numbers between -1 and 1 including -1 and 1

Note: we can write that as  which in interval notation would look like . The square brackets tell us to include the endpoints.

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