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Math Memory - Zer Netmouse
February 23rd, 2007
01:22 pm

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Math Memory
A friend's post reminded me how it can be hard to remember math definitions, and of one of my favorites to remember.

--Did you ever learn the soh-cah-toa mnemonic?

My math teacher once walked into the room with a bucket of water, took her shoe and sock off, dipped her toe into the water and gave an exaggerated sigh of relief. We all stared at her until she explained that this is an important geometry mnemonic - soak a toe (ah!)

Soh --Sine (Opposite over Hypotenuse)
Cah --Cosine (adjacent over Hypotenuse)
Toa --Tangent (opposite over adjacent)

(if this is unfamiliar, see the pretty picture and explanation)

(19 comments | Leave a comment)

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From:mrissa
Date:February 23rd, 2007 06:39 pm (UTC)
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Yep, we did that one!

Like the picture, too.
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From:alicebentley
Date:February 23rd, 2007 06:46 pm (UTC)
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I remember it well.

My other favorite mnemonic is HONClBrIF - the naturally occuring diatomic elements - Hydrogen, Oxygen, Nitrogen, Clorine, Bromene, Iodine and Florine.
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From:dagibbs
Date:February 23rd, 2007 07:12 pm (UTC)
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I remember socahtoa, and bodmas (or bomdas).
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From:netmouse
Date:February 23rd, 2007 08:17 pm (UTC)
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what's bodmas for?
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From:dagibbs
Date:February 23rd, 2007 08:38 pm (UTC)
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Precedence of operators: brackets, of, division/multiplication, addition/substraction.
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From:metalfatigue0
Date:February 23rd, 2007 09:10 pm (UTC)
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Or "Hug my dear Aunt Sally." Which leaves out exponentiation.
From:lvaughn
Date:February 23rd, 2007 09:41 pm (UTC)
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I was taught "Please excuse my dear aunt Sally", which gets exponentiation (and does parenthesis instead of brackets).
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From:dd_b
Date:February 23rd, 2007 07:21 pm (UTC)
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Nope, I've never seen that before. I learned the trig functions as "wrapping functions", the rolling circle, and the application to triangles was derived later, when there was no possibility of confusion over what bit was which, I think.
From:jer_
Date:February 23rd, 2007 08:32 pm (UTC)
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That's the way I've always known them...to me it's a much more intuitive method (which helped me not one bit when I swapped my numerator and denominator for tangent and cotangent today on a test... SPLENDID!)
From:threemeow
Date:February 23rd, 2007 08:06 pm (UTC)
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Oscar Has (Opposite over Hypotenuse)
A Headache (adjacent over Hypotenuse)
Over Algebra (opposite over adjacent)
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From:sorcycat
Date:February 23rd, 2007 08:10 pm (UTC)
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I never learned that one, but I recall one from calculus.

Hodehi minus hideho over hoho

This is a mnemonic
for the Quotient Rule. Though I must admit I remembered the mnemonic but I had to look up what it was for. :)
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From:netmouse
Date:February 23rd, 2007 08:16 pm (UTC)
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oh yeah.... we learned that one too, but I had forgotten it.
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From:metalfatigue0
Date:February 23rd, 2007 09:09 pm (UTC)
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If I tried to use that mnemonic, I'd always wind up swapping hideho and hodehi. I was taught the trickle-down rule: the thing on top gets differentiated first.
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From:metalfatigue0
Date:February 23rd, 2007 09:08 pm (UTC)
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My eyes took in the second sentence of your post before the rest, probably because it was short and surrounded by blank space.

My first association with "soh-cah-toa" was Ultima IV. "Cah…that's the Mantra of Compassion, right?"

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From:boywhocantsayno
Date:February 24th, 2007 04:35 am (UTC)
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I don't recall learning the mnemonic with the physical demonstration, but I do recall the made-up word "sohcahtoa".

Then again, I learned that stuff about 25 years ago, so it's quite possible that it was taught that way and I'm just not remembering.
From:tlatoani
Date:February 24th, 2007 05:37 am (UTC)
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I learned soh-cah-toa, but not with the live foot demonstration.
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From:kyril
Date:February 24th, 2007 03:47 pm (UTC)
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I don't know if it was the teacher or my mental associations, but "Sohcahtoa" was an Indian princess or something.

I remember the phrase "Please Excuse My Dear Aunt Sally" though I think I had drilled enough problems by the time I heard it to not need it.

Better Be Right Or Your Great Big Venture Goes West (resistor color codes) still comes to mind.

There's one for the planets but I don't remember it. Though now it can't end in "pizza" any more.
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From:metalfatigue0
Date:February 25th, 2007 06:56 am (UTC)
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Bad Booze Rots Our Young Guts, But Vodka Goes Well.

There's another one I know that's not appropriate for polite conversation.

From:ex_vergil895
Date:February 24th, 2007 04:53 pm (UTC)
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Hehe, thanks for reminding me we had the same math teacher ;)
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