Confused about mix of polite/impolite forms in genki workbook


While doing [these exercises](https://sethclydesdale.github.io/genki-study-
resources/lessons-3rd/lesson-9/workbook-7/) on the particle から from Seth
Clythesdale's online Genki Workbook, I noticed that in the provided answer to
the exercise I, question 3, polite and impolite forms are mixed, at least to
my untrained Japanese abilities:

> みなみさんは踊るのが上手だから、すごく人気があります。
>
> Minami is very popular because she is good at dancing.

We have あります at the end, but before the から, we have だ and not です. Is だから
different from から? Because in the [lesson 9 of the
textbook](https://sethclydesdale.github.io/genki-study-resources/#lesson-9),
only から is discussed, but not だから.




Like others have mentioned in the comments and such, its possible to have ですから
and still end with a polite form (e.g あります), but you will mainly come across
the plain form with a polite form ending like your [workbook practice
problems](https://sethclydesdale.github.io/genki-study-
resources/lessons/lesson-9/grammar-10/) in my experience.

But I wanted to address this portion of your question since I see it equally
as important, if not more important:

> Is だから different from から? Because in the lesson 9 of the textbook, only から
> is discussed, but not だから

Now I cannot speak on when / how Genki teaches you this as I have never used
it before, but から can mean 2 different things depending on what comes before
it.

  1. から can mean "from" if there is a noun beforehand without だ (です in polite form)

Example:

> 学校から来ました。
>
> I came from school.

Our noun before から is 学校 (school) and since there is no だ this means "from" in
this case.

  2. から means "because" if there is a verb, い adjective, な adjective, or noun beforehand. However, for this meaning, the な adjective and noun will have a だ (です in polite form) before the から.

Example:

> 黒い猫だから好きです。
>
> I like it because its a black cat.

Our noun before から is 猫 (cat) and since there is a だ before the から this means
"because" in this case.

Just as a side note, those workbook practice problems linked above seem to all
focus on the "because" meaning / usage.

