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## Homework Statement

What's the 39th derivative of cosx?

## Homework Equations

1st dy/dx: -sin x

2nd: -cosx

3rd: sinx

4th; cosx

## The Attempt at a Solution

So it repeats every 4

so I used 39/4 and for a remainder of 3 so is is the 3rd one down?

I got sin x but I don't know if that's the way its supposed to be done ( the remainder is the number of derivative the answer is)