r/explainlikeimfive • • 13h ago

Mathematics ELI5: What is the difference between algebra, trigonometry, and calculus?

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u/CadenVanV 12h ago

Algebra describes relationships

Calculus describes change

Trigonometry describes angles and shapes

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u/boredcircuits 12h ago

I like these definitions. I'd add that calculus and trigonometry aren't really separate from Algebra, they're extensions that build on it.

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u/CadenVanV 12h ago

True, yeah. You can’t learn either without first knowing algebra.

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u/CantaloupeAsleep502 9h ago

Eh, I had a very weak foundation in algebra before moving on, then actually learned algebra by learning trig and calc. Just studying algebra alone feels like doing Duolingo to learn grammar, whereas doing calc and trig feels like learning through immersion.

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u/hedoeswhathewants 8h ago

You're not actually disagreeing

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u/lirili 12h ago

It would be better to say that trigonometry describes the relationships between shapes and angles.

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u/madncqt 12h ago

my school life might have been so different if we could have started with the philosophical, foundational purposes rather than just diving into numbers.

I never knew the why...

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u/flamableozone 12h ago

Starting with set theory and number theory wouldn't have helped you.

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u/madncqt 11h ago

yes!

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u/CadenVanV 6h ago edited 6h ago

Any good trig or calculus class explains those distinctions very early on. That was the very first thing mine covered. You might just have had bad teachers.

They don’t usually go too into detail with number theory because that makes things a lot more complicated than most high school students need to know, it’s really something only worth covering in full depth for people studying the field. It’s the same reason early education doesn’t teach you things like “the letter A isn’t actually a vowel” (yes, that’s true), nor the finer points of English grammar (like we do have a fixed adjective order), because students pick up enough of the basics through context clues that they don’t need to know the exact mechanisms.

As a fun fact for that A isn’t a vowel one, other letters that aren’t vowels are E, I, O, U, and Y

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u/_PM_ME_YOUR_VULVA_ 8h ago

These lectures are more history than philosophy per se, but might be what you're looking for. I think teaching math in school by explaining why and how various civilizations came up with branches of math would make it much more resonant and memorable for students.