# Question #94080

##### 2 Answers

#### Explanation:

The fastest and easiest solution is assuming the interval

The cosine function is zero at integer multiples of

Therefore,

Therefore, the only zero between

If the interval insists that you use radians (i.e., 20 radians and 50 radians), then the answer is only more difficult because there are more solutions.

The cosine function is zero at

So the function

There are nineteen integers that work starting at

Just want to add some stuff :)

#### Explanation:

This is all radians btw.

It is true, that when we look at the function

If we want to make that more general, we could write:

In this case we have

The we want to look at the interval of

This can be written as:

Isolate (k).

This approximates to:

Because we know

The total amount of solutions is