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Deleted

Villa Park, California

Dec 22, 2009 @ 19:45:00

Angles less than 180? can be acute if they are less than 90? and obtuse if they are greater than 90?. Angles greater than 180? apparently have only one name, which is reflex. I'm wondering if if mathematicians have ever coined names for reflex angles greater and less than 270?.

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Pantagruel

salford, Pennsylvania

#2

Dec 22, 2009 @ 20:40:31

they would have, if they knew how to 69

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NikiNiki

Deleted

Villa Park, California

#3

Dec 22, 2009 @ 23:27:10

Anyway, I'm doing this science project, and it involves some angles. Mostly they are acute and obtuse. So far only one is a reflex angle greater than 270?, so maybe I don't need a name. Pi is 90?, and beta is about 71?.

The acute angles are pi/2 - 3*beta/2, 0, beta/2, pi/2 - beta/2, pi/3, beta, pi/2.

The obtuse angles are 3beta/2, tetrahedral angle, pi/2 + beta/2, 2beta, 2pi-3beta, pi.

The reflex angles are pi/2 + 3*beta/2, 3beta, 3pi/2, 4beta, 2pi.

Edit: Pi is 180?, not 90?.

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Edited: December 22, 2009 @ 23:49

squall

Deleted

Brisbane, Australia

#4

Dec 22, 2009 @ 23:37:58

...I have no idea what you're on about then again probably different teaching methods.

I can assure you that for:
0-90 = Acute
90 = Right angle
90-180 = Obtuse
180 = Straight? (not sure on the name)
180-360 = Reflex

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NikiNiki

Deleted

Villa Park, California

#5

Dec 22, 2009 @ 23:52:57

@squall Said

...I have no idea what you're on about then again probably different teaching methods.

I can assure you that for:
0-90 = Acute
90 = Right angle
90-180 = Obtuse
180 = Straight? (not sure on the name)
180-360 = Reflex

Yes, that's the way the math books in the United States teach it. I think a word to distinguish angles larger and smaller than 270? would be helpful. I think I can find a good example for why.

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squall

Deleted

Brisbane, Australia

#6

Dec 22, 2009 @ 23:55:37

@NikiNiki Said

Yes, that's the way the math books in the United States teach it. I think a word to distinguish angles larger and smaller than 270? would be helpful. I think I can find a good example for why.

Lazy Mathematicians?

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NikiNiki

Deleted

Villa Park, California

#7

Dec 23, 2009 @ 13:01:27

@squall Said

Lazy Mathematicians?

Well, that is an interesting possibility. Being a college professor must be easier than working retail or construction. How hard can scribbling with a pencil be?

Also, I think in common usage, angles come in pairs. For example, in my science project, the angle formed by the three atoms of a propane molecule is about 110?. That angle has an associated reflex angle of 250?. When I think of the molecule, I think of the 110?. A Wikipedia article calls this angle, the tetrahedral angle.

The three atoms of the propane molecule form a circle. If we add a fourth atom to form a butane molecule, the atoms may form the same circle. If we draw lines from the circle's center to the atoms, we get a concave pentagon. The angle formed by the circle's center and the first and fourth atom is about 284?, which is a reflex angle.

Maybe I should stop and ask if I'm making any sense.

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WeNowSix

Deleted

Anaheim, California

#8

Dec 26, 2009 @ 14:13:51

@NikiNiki Said

Well, that is an interesting possibility. Being a college professor must be easier than working retail or construction. How hard can scribbling with a pencil be?

Also, I think in common usage, angles come in pairs. For example, in my science project, the angle formed by the three atoms of a propane molecule is about 110?. That angle has an associated reflex angle of 250?. When I think of the molecule, I think of the 110?. A Wikipedia article calls this angle, the tetrahedral angle.

The three atoms of the propane molecule form a circle. If we add a fourth atom to form a butane molecule, the atoms may form the same circle. If we draw lines from the circle's center to the atoms, we get a concave pentagon. The angle formed by the circle's center and the first and fourth atom is about 284?, which is a reflex angle.

Maybe I should stop and ask if I'm making any sense.

Why would you need a word, which differentiates between reflex angles greater and less than 270??

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NikiNiki

Deleted

Villa Park, California

#9

Dec 26, 2009 @ 21:22:11

Maybe I wouldn't need different words for angles greater and lessor than 270?. I had thought having different words might be a good thing because I wanted to find a simple way to represent my angles. The angles on my angle list have complicated names, which are complements and supplements of various fractions of acos(1/3); so I thought about using the arcosines as simpler names. For example, sixty degrees is arcosine of 1/2, but 300? also is arcosine of 1/2. Since 60? is acute and 300? is reflex, there is no conflict, but I wondered what would happen if two reflex angles had equal arcosines. I haven't found an example, so maybe it's not a problem.

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WeNowSix

Deleted

Anaheim, California

#10

Dec 27, 2009 @ 13:08:08

How about you say angles are concave and convex. Sixty degrees is acos(1/2) and concave. Three hundred degrees is acos(1/2) and convex.

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NikiNiki

Deleted

Villa Park, California

#11

Dec 27, 2009 @ 16:23:14

That's a rather good idea. The categories of angles should be two rather than four. Even so, some of the angles have cosines like one third of radical six or five ninths radical three. The further the point from the origin; the larger the integers under the radical.

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TheMatrix

Sugarland, Texas

#12

Jan 03, 2010 @ 17:59:24

@NikiNiki Said

Anyway, I'm doing this science project, and it involves some angles. Mostly they are acute and obtuse. So far only one is a reflex angle greater than 270?, so maybe I don't need a name. Pi is 90?, and beta is about 71?.

The acute angles are pi/2 - 3*beta/2, 0, beta/2, pi/2 - beta/2, pi/3, beta, pi/2.

The obtuse angles are 3beta/2, tetrahedral angle, pi/2 + beta/2, 2beta, 2pi-3beta, pi.

The reflex angles are pi/2 + 3*beta/2, 3beta, 3pi/2, 4beta, 2pi.

Edit: Pi is 180?, not 90?.

I don't think I can safely say that 2pi > 180 deg, and pi = 90 degs, neither obtuse nor acute.

Isn't a tetrahedral angle 2atan(sqrt(2)) = 109.47?

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NikiNiki

Deleted

Villa Park, California

#13

Jan 03, 2010 @ 19:28:17

@TheMatrix Said

I don't think I can safely say that 2pi > 180 deg, and pi = 90 degs, neither obtuse nor acute.

Isn't a tetrahedral angle 2atan(sqrt(2)) = 109.47?

Well yes, that's right. 2pi is 360?, and pi/2 = 90?. While they may be cute,

like me, 8)

they are neither acute, obtuse, or reflex.

I think of the tetrahedral angle as acos(-1/3), so it's arctangent would be its arcsine divided its arcosine or (2/3)*2^.5 divided by (-1/3), which is indeed -2*2^.5 or 109.47?. I don't know why Excel returns -70.53?.

The ? is alt 167 on my keyboard.

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ADUB87

Deleted

Inside a triangle, Bermuda

#14

Jan 03, 2010 @ 19:42:44

@NikiNiki Said

Well yes, that's right. 2pi is 360?, and pi/2 = 90?. While they may be cute,

like me, 8)

they are neither acute, obtuse, or reflex.

I think of the tetrahedral angle as acos(-1/3), so it's arctangent would be its arcsine divided its arcosine or (2/3)*2^.5 divided by (-1/3), which is indeed -2*2^.5 or 109.47?. I don't know why Excel returns -70.53?.

The ? is alt 167 on my keyboard.

Are you a peodophile disguising yourself as a 13 year old girl that looks like miley cyrus? lol... If not you must be the smartest 13 year year old ever!

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dmastr

Palatka, Florida

#15

Jan 03, 2010 @ 19:44:34

@ADUB87 Said

Are you a peodophile disguising yourself as a 13 year old girl that looks like miley cyrus? lol... If not you must be the smartest 13 year year old ever!

hahahaha,i was just thinkin the same thing yo

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