Questions & Answers about Tato rychlost je příliš vysoká.
Tato means this and it has to agree with the noun rychlost.
In Czech, this changes form depending on the gender and case of the noun:
Because rychlost is a feminine singular noun and here it is in the nominative, the correct form is tato.
You may also hear ta rychlost in less careful or more conversational speech, but tato rychlost is the clear standard form.
Yes, rychlost is feminine.
A lot of Czech feminine nouns do end in -a, but not all of them. Nouns ending in -ost are very often feminine, for example:
- rychlost = speed
- radost = joy
- možnost = possibility
So even though rychlost ends in a consonant, it is still feminine.