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.