Help with a math problem?

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ID:184166
 
Dec 13 2006, 11:12 am


How would I go about doing this?

Thanks!
Dec 13 2006, 11:25 am
I forgot how to do this but its either 2 or 3.
Dec 13 2006, 11:38 am
Did you put the right answers up? I keep getting 140 degrees as the answer...
Dec 13 2006, 12:19 pm
The m notation is a little odd, so that threw me a minute. Why they didn't say angle AOD instead of mAD I have no idea. And of course, forgetting the ° symbol was moronic. Bad textbook! No biscuit!

Anyway, assuming these idiots meant to say the angle AOD (the angle of the AD curve) is 40°, we have just enough information to work with. Because DE and AY are parallel, AOD and OAY are inner transverse angles; they're both 40°. Meanwhile, AOD is an isosceles triangle; the angles DAO and ADO are identical. Since DAO + ADO + AOD = 180°, that reduces to 2(DAO) + 40° = 180°, or DAO = ADO = 70°. Since we know DAO + OAY = DAY, then 70° + 40° = 110° = DAY.

[edit]
This is a lot easier to visualize if you draw a line from O to A.

Lummox JR
Dec 13 2006, 12:29 pm
In response to Lummox JR
Lummox JR wrote:
This is a lot easier to visualize if you draw a line from O to A.

The m notation is a little odd, so that threw me a minute. Why they didn't say angle AOD instead of mAD I have no idea. And of course, forgetting the ° symbol was moronic. Bad textbook! No biscuit!

This isn't even a textbook, it's a state exam :\ Go New York Department of Education!

Anyway, assuming these idiots meant to say the angle AOD (the angle of the AD curve) is 40°, we have just enough information to work with. Because DE and AY are parallel, AOD and OAY are inner transverse angles; they're both 40°.

Meanwhile, AOD is an isosceles triangle; the angles DAO and ADO are identical.

I'm sorry, my last year geometry teacher was pretty bad; how do you know AOD is isosceles?

Since DAO + ADO + AOD = 180°, that reduces to 2(DAO) + 40° = 180°, or DAO = ADO = 70°. Since we know DAO + OAY = DAY, then 70° + 40° = 110° = DAY.

Alright, I understand all that, thanks. I just don't understand how AOD is isosceles.

Thanks :]


Dec 13 2006, 12:35 pm
In response to Airjoe
Are you taking the regents?
Dec 13 2006, 12:36 pm
In response to Xx Dark Wizard xX
Yes, I take the Math B in January.
Dec 13 2006, 12:39 pm
In response to Airjoe
I never took math B, I never needed to. The tests are overrated, they are much easier than they are said to be. I am suprised thats on the math B.
Dec 13 2006, 12:40 pm
In response to Xx Dark Wizard xX
Then solve it.

How is that triangle congruent like Lummox said?
Dec 13 2006, 12:48 pm
In response to Airjoe
I think Lummox said the answear was 110 degrees (go me not knowing the stupid code for the degree symbol)

and Lummox, apparently they are now using m
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Dec 13 2006, 12:49 pm
In response to Shlaklava
I know the answer is 110 degrees. The answer is online.

However, I don't know how to solve it, hence I asked here. Lummox helped, but part of his explanation I didn't understand.
Dec 13 2006, 2:11 pm
In response to Airjoe
Airjoe wrote:
Alright, I understand all that, thanks. I just don't understand how AOD is isosceles.

Thanks :]

Well, you've got a circle, so the line from O to A is just another radius. Thus you have an isosceles triangle.
Dec 13 2006, 5:21 pm
In response to Airjoe
Airjoe wrote:
I know the answer is 110 degrees. The answer is online.

However, I don't know how to solve it, hence I asked here. Lummox helped, but part of his explanation I didn't understand.

You asked how I knew AOD is an isosceles triangle. I probably should have explained that part. D and A are both on the circle, and O is the center of the circle. Thus, DO and AO are both as long as the radius of the circle. Since they're the same length, the triangle they form is isosceles. That means the angles opposite those sides are equal as well.

Lummox JR
Dec 13 2006, 5:24 pm
In response to Lummox JR
Thanks for all the help :]
Dec 14 2006, 6:24 am
In response to Airjoe
That's how the Saxon system for our PreCalc writes all our angles and such. A lesson per day... 30 questions... Jeez...
Dec 14 2006, 10:27 am
In response to Lummox JR
m means measure of the angle following. I think they used m to get you more familiar with it. It's not exactly needed, but if you happen to come across it and you don't know what it means, well, you just might be in trouble.
Dec 14 2006, 11:35 am
In response to CaptFalcon33035
I'd say it's pretty damned stupid to come up with an alternative notation when a better notation is already available and accepted. But then, I think a lot of math is stupid in general (too discrete).
Dec 14 2006, 12:03 pm
In response to CaptFalcon33035
CaptFalcon33035 wrote:
m means measure of the angle following. I think they used m to get you more familiar with it. It's not exactly needed, but if you happen to come across it and you don't know what it means, well, you just might be in trouble.

It's still freaking stupid. The angle notation was already well understood by pretty much everybody with an elementary math background, and it has the advantage of not being easily confused with algebra. In algebra, m would be a variable.

Lummox JR
Dec 14 2006, 12:55 pm
In response to Lummox JR
Lummox JR wrote:
CaptFalcon33035 wrote:
m means measure of the angle following. I think they used m to get you more familiar with it. It's not exactly needed, but if you happen to come across it and you don't know what it means, well, you just might be in trouble.

It's still freaking stupid. The angle notation was already well understood by pretty much everybody with an elementary math background, and it has the advantage of not being easily confused with algebra. In algebra, m would be a variable.

Lummox JR

They just started teaching that in our school this year. It confused me and made me get a 98% on a test because I was like "m is less then A? Or m times angle A?".
Dec 15 2006, 11:13 pm
In response to Lummox JR
Lummox JR wrote:
CaptFalcon33035 wrote:
m means measure of the angle following. I think they used m to get you more familiar with it. It's not exactly needed, but if you happen to come across it and you don't know what it means, well, you just might be in trouble.

It's still freaking stupid.

Agreed. That "mAD" notation is the most stupid thing I've ever seen from a maths textbook (and believe me when I say I've seen some boneheaded things in maths textbooks).

I would like to introduce whoever dreamed up that nonsense to my Calculus textbook, by way of an overhead swing. Given the size and weight of that textbook, this is no small threat. ;-)
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