According to the book I am reading, "Sakura is beautiful" is written as

> さくらはきれいです

and "Sakura is a beautiful flower" is

> さくらはきれいなはなです

,but when using たかい the na form isn't used. For example:

> ふじさんはたかいで
>
> ふじさんはたかいやまです

But not

> ふじさんはたかいなやまです
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2018-10-11T12:03:26.587
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adjectives i-adjectives na-adjectives
Using い and な adjectives
This is unfortunately one of the parts of Japanese that you'll have to just
remember. Some Adjectives can also be said with い AND な。

It happens with a few adjectives, and this occurs in daily speech as well.

In general, especially when you're first learning, I would simply use the い
form for all ”い” adjectives. Realize that there are specific な only adjectives
as well (which do not take い).

If you want to delve further, this has been answered in depth here:

[Adjectives functioning both as イ- and
ナ-adjective](https://japanese.stackexchange.com/questions/6675/adjectives-
functioning-both-as-%E3%82%A4-and-%E3%83%8A-adjective)
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2018-10-11T13:37:41.100
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It is because there are い adjectives and な adjectives.

The attributive form of a な adjective ends with な, such as in **きれいな** はな.

The attributive form of an い adjective ends with い, such as in **たかい** やま.

When they are placed before です, in the case of an い adjective, you use the
plain form, such as in ふじさんは **たかい** です. In the case of a な adjective, you use
the stem of the word, such as in さくらは **きれい** です.
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answer