Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Trigonometry is regular. It follows the -ies Conversion rule.
Use plural verbs: "The trigonometries are ready" (not "is ready").
Yes. The plural trigonometries is standard across all English variants.
The word trigonometry follows the standard English pluralization rule. When forming the plural, trigonometry becomes trigonometries. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why trigonometry becomes trigonometries helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using trigonometries in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The trigonometries are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.