Author Topic: Geometry help  (Read 510 times)

Offline BlckMgk

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Geometry help
« on: April 20, 2007, 02:26:59 PM »
Its been a while since I did geometry in school but I need some help with some right triangle measurements.

I have a leg length of 2 inches and 4 inches and they intersect at a right angle (90degrees)

What I need to know is:
The angle where the hypotnous and the 4inch leg meet.
The angle where the 2inch leg and the hypotnous meet.
And the length of the hypotnous.

From trying to refresh by searching the web I found the Sine, Cosine, and Tangent formulas but forgot how to apply them.

Please help!

-Blck

Offline megadud

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Geometry help
« Reply #1 on: April 20, 2007, 02:35:36 PM »
45 you're welcome :aok

Offline vorticon

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Geometry help
« Reply #2 on: April 20, 2007, 02:44:46 PM »
short leg angle where it meets the hypotenuse is 28.64 degrees (1/ (2/4 *tan))
the other angle is 64.36 degrees (90 - 28.64)

the length is 4. 47(4/ sine(64.36))


but dont take my word for it, i was never to great at it when i was doing every day, let alone after a couple years of not doing it at all (or actually, letting the fancy construction calculator figure it out for me)
« Last Edit: April 20, 2007, 02:49:56 PM by vorticon »

Offline john9001

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Geometry help
« Reply #3 on: April 20, 2007, 03:08:22 PM »
my calculating machine says

hypotenuse= 4.4721

angle for 4 inch leg=26.565

angle for 2 inch leg=63.435

Offline BlckMgk

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Geometry help
« Reply #4 on: April 20, 2007, 03:16:55 PM »
you guys got the same length, but different angles, how come?

-Blck..

BTW thanks!

Offline kamilyun

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Geometry help
« Reply #5 on: April 20, 2007, 03:24:50 PM »
a ------- 4 in ------------------- b
|                                      
                               
2                          
i                  
n            
           
|      
c

Length of hyp = (4^2 + 2^2)^1/2 = 20^1/2 = 2*5^1/2... "the square root of 20" or "two times the square root of five"

soh cah toa

sin = opposite over hyp
cos = adjacent over hyp
tan = opposite over adjacent

tan b = 2/4 = 0.5; b = tan^-1 (0.5) = i don't have my nice calc with me
tan c = 4/2 = 2; c = tan^-1 of (2.0) = ditto

Edit:  sweet online scientific calculator

inverse tanget of 0.5 = 26.57 degrees, this is angle b
inverse tanget of 2.0 = 63.43 degrees, this is angle c

They add up to 90...
« Last Edit: April 20, 2007, 03:29:17 PM by kamilyun »

Offline Dux

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Geometry help
« Reply #6 on: April 20, 2007, 03:26:03 PM »
SOHCAHTOA! :aok

Glad somebody else remembers that. :)
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Offline vorticon

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« Reply #7 on: April 20, 2007, 03:32:22 PM »
Quote
Originally posted by BlckMgk
you guys got the same length, but different angles, how come?

-Blck..

BTW thanks!


i was using the windows scientific calculator, and probably pressed the buttons in the wrong order.

Offline SIK1

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Geometry help
« Reply #8 on: April 20, 2007, 03:35:22 PM »
Using pathagareom therum (2^2+4^2)= hypotonus^2.

Hypotonus= 4.47"

using the law of sines the small angle is =27*
again using the law of sines the large angle is =63*
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Offline FastFwd

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Geometry help
« Reply #9 on: April 23, 2007, 05:06:16 AM »
Quote
Originally posted by john9001
my calculating machine says

hypotenuse= 4.4721

angle for 4 inch leg=26.565

angle for 2 inch leg=63.435


Agreed.

storch

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Geometry help
« Reply #10 on: April 23, 2007, 06:34:24 AM »
Quote
Originally posted by john9001
my calculating machine says

hypotenuse= 4.4721

angle for 4 inch leg=26.565

angle for 2 inch leg=63.435
yup

Offline SIK1

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« Reply #11 on: April 23, 2007, 09:25:29 AM »
You actually don't have enough significant figures to have anything less than a whole degree. Truthfuly the length of the hypotanus should be no more than two sig figs rounding up to 4.5".
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Offline Jackal1

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Geometry help
« Reply #12 on: April 23, 2007, 09:37:39 AM »
OK, while you have those  brains fired up. :)

A cylindrical container that is 5 1/2 " tall with a circumfrence of 6 1/2 "............
How many ounces will it hold?
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Offline Mak333

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« Reply #13 on: April 23, 2007, 09:54:17 AM »
Quote
Originally posted by Jackal1
OK, while you have those  brains fired up. :)

A cylindrical container that is 5 1/2 " tall with a circumfrence of 6 1/2 "............
How many ounces will it hold?


First off circumference is 2xPixRadius = 6.5

You need to find the area which is Pi x Radius^2

6.5/(2xPi) = Radius = 1.03 inches

(pi)(1.03^2)

3.36 is the area of the base

(3.36)(5.5) = 18.5 inches squared (volume)

I am not going to go any further because I have to go to my speech 101 class, but someone can figure out the ounces.
Mak

Offline SIK1

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Geometry help
« Reply #14 on: April 23, 2007, 12:30:34 PM »
Hmmm, I get 3.33"^2 for the area of the circle, and 18.3"^3 for the volume of the cylinder.

1 fl. oz.= 1.804"^3 so if you take the volume of the cylinder 18.3"^3 divide by 1.804"^3 you will get the fluid ounces that the cylinder will hold. I get 10.1 fl oz.
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