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Help with maths

Almercenary
By Almercenary
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So I have a few questions I need help with.

This one (probs easy, just don't know it off the top of my head):

 

Find the Area

post-42897-0-91393700-1398938605.jpg

 

And also can someone check if my working is correct and I have the correct answer in the end (my diagram isn't great, mainly for the pro-numerals).

 

Find the radius of the smaller circle, if the radius of the bigger circle is 1.

post-42897-0-15670100-1398939459.png

 
Working:
OC=√2r
OA=1
OC+CA=1
√2r+r=1
r(√2+1)=1
r=1/1+√2
r=√2-1 which is around about equal to 0.414213

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Posted (edited)

my guessing is that the first one probably just is half of a circle with a radius of 8 cm. (you have to take the part below the x axis and put it in the hole above it)

please correct me if i'm wrong

 

edit:

-since you are 15 years (according to your profile) you should be able to complete the first one now

-i am guessing you have to calculate "r" in the second question (the radius of the smal circle)?

Edited by darkspeedy26

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my guessing is that the first one probably just is half of a circle with a radius of 8 cm. (you have to take the part below the x axis and put it in the hole above it)

please correct me if i'm wrong

 

edit:

-since you are 15 years (according to your profile) you should be able to complete the first one now

-i am guessing you have to calculate "r" in the second question (the radius of the smal circle)?

Yes, you have to caculate the radius of the smaller circle, I edited it in.

The first one you just use Pie x Radius² and then half it cause its a semi circle

 

@Almercenary

 

Yeah, got it now, thanks, welll I atleast got the same answer as my buddy so should be all good.

Beneath this mask there is more than flesh. Beneath this mask there is an idea, Mr. Creedy, and ideas are bulletproof.

As I get older I get angrier more cynical, meaner. I feel some warning posts coming. I feel a ban coming. I was warned.

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Yes, you have to caculate the radius of the smaller circle, I edited it in.

 

Yeah, got it now, thanks, welll I atleast got the same answer as my buddy so should be all good.

No problem mate

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Posted

 

So I have a few questions I need help with.

This one (probs easy, just don't know it off the top of my head):

 

Find the Area

attachicon.gifMaths123.JPG

 

 

I got 12.56 for that [(3.14*8)/2]

as for the other one, I'll try it later when I get home if someone hasn't already tried it.

edit: some things that I got:

A=(0.71,0.71)

C=(0.415,0.415)

D=(0.415, 0)

R=0.415

2R=0.83

Woo!

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Posted

rounding is hard :D

 

0.414213 is wrong, 0,414214

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Posted

h. is just half the area of a circle at a radius of 8 (or diameter of 16).

The inverted and protruding semicircle cancel each other out.

 

A = pi x r^2

 

So... 

 

pi x 8^2

 

therefore 

 

A = 201.06

 

Half that and you get...

 

100.53

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Posted
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I got 12.56 for that [(3.14*8)/2]

as for the other one, I'll try it later when I get home if someone hasn't already tried it.

edit: some things that I got:

A=(0.71,0.71)

C=(0.415,0.415)

D=(0.415, 0)

R=0.415

2R=0.83

For 1st one wouldn't it be this because it's area.

π*8^2=64π

64π/2=32π

32π=100.531

 

rounding is hard :D

 

0.414213 is wrong, 0,414214

 

Im tired, cut me some slack  :D

Thanks!!!

Beneath this mask there is more than flesh. Beneath this mask there is an idea, Mr. Creedy, and ideas are bulletproof.

As I get older I get angrier more cynical, meaner. I feel some warning posts coming. I feel a ban coming. I was warned.

CPU-i5 2400 GPU-Sapphire Radeon HD 7970 OC Mobo-H67MA-D2H-B3 Ram-G.Skill Ripjaws 8gb 1333mhz Case-Fractal Define R4 PSU-Corsair CX750 Storage-Samsung EVO 250gb, 1tb WD Black,Hitachi 1tb Other stuff-Corsair K90, M90 Cooling-3x 140mm Fractal fans Sound-Sennheiser HD438 headphones
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h. is just half the area of a circle at a radius of 8 (or diameter of 16)

A = pi x r^2

So... 

pi x 8^2

therefore 

A = 201.06

Halved, because it's a semi circle.

Beneath this mask there is more than flesh. Beneath this mask there is an idea, Mr. Creedy, and ideas are bulletproof.

As I get older I get angrier more cynical, meaner. I feel some warning posts coming. I feel a ban coming. I was warned.

CPU-i5 2400 GPU-Sapphire Radeon HD 7970 OC Mobo-H67MA-D2H-B3 Ram-G.Skill Ripjaws 8gb 1333mhz Case-Fractal Define R4 PSU-Corsair CX750 Storage-Samsung EVO 250gb, 1tb WD Black,Hitachi 1tb Other stuff-Corsair K90, M90 Cooling-3x 140mm Fractal fans Sound-Sennheiser HD438 headphones
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Posted

That's the half of ing yang thing in Asian culture, right?

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