?Refer to Wiki: List of Maclaurin series of some common functions

Maclaurin series of these common functions are very useful, which we really want to memorize.

## Example

Solve:

- This Maclaurin series has a clear pattern of cos(x) Maclaurin series:

- In this case, it?s:

- So we could convert the series back to the trig function:

## Example

Solve:

## Example

Solve:

- Looks quite a complicated series, but we look at the factorial dominators, we found that resembles the pattern of the sin(x)’s maclaurin series.
- By comparing to the sin(x) maclaurin series, we notice that x = ?/2, and all the rest are the same.
- So rewrite the series to the function:

- And we get the result is 1.