Latin Noun Adjective Agreement

When the noun is third dec, how do u know if u shud use a first or second dec. adjective?

You don't need to know. Adjectives don't change declensions and nouns don't change declensions. Therefore is you had a 3rd declension noun like lux, lucis f (light) and you wanted to say 'bright light', bright is 'clarus, a, um' and is a 1st/2nd declension adjective, you would have to match the adjective to the noun even though they are different declensions. Hence you would get lux clara 'bright light'.

Hope this helps. Just remember that nouns and adjectives are certain declensions by nature and will not change. The words can still match in case, number, and gender even though their endings will not look alike.

that helped soooooooooo much Thank you!

You're quite welcome!

Thanks

thank you so much one day left in class an i am only finding this now thank you non the less

Thanks

you explained this sooooo much better than my latin teacher did.

How do you know whether to use 2nd or 3rd neuter?

Thank you !