In Calc's Manual 2.5.2: Section: Rewrite Rules,
https://www.gnu.org/software/emacs/manual/html_mono/calc.html#Rewrites-Tutorial
There is the following typo.

In the Exercise-1 shows following:

```
1:  [merge, secsqr]          1:  [a/x + b/x := (a + b)/x, ... ]
    .                                 .

    ' [merge,sinsqr] RET          =
```

You can see, it says that when entering [merge, sinsqr] it becomes
[merge, secsqr].

I believe the `sinsqr` was supposed to be `secsqr`.
(In fact there is no mention of `sinsqr` in the whole manual).

Garid.