Circumference / area ratio?

yermum · 12 Jun 2008 at 22:29

Why is it that my baking tin which measures 8" x 8" has an area of 64", but the one that measures 9" x 7" is only 63"? If the total outside is the same, why isn't the inside?

gumbald · 12 Jun 2008 at 22:31

It's an optimisation problem.

Weebull · 12 Jun 2008 at 22:32

Because it's not a "perfect" oval, and the area gained by stretching out one axis 1" doesn't make up for the area lost along the other axis.

I mean duh.

daz · 12 Jun 2008 at 22:32

Weebull · 12 Jun 2008 at 22:33

Also, I hope you stopped halfway through cooking and rushed to the internet to ask this.

Makhaira · 12 Jun 2008 at 22:34

If you had some strange cookie-related maths fixation, you could find the best dimensions for an area by differentiating to find the optimum ratio...

yermum · 12 Jun 2008 at 22:39

Weebull said:
Also, I hope you stopped halfway through cooking and rushed to the internet to ask this.

No, just wondered why 2 cakes turned out differently. It hadn't occurred to me that the 2 tins would have diferent areas.

Vixen · 12 Jun 2008 at 23:07

Um, 8x8 = 64, 9x7 = 63...

p4radox · 12 Jun 2008 at 23:10

Vixen said:
Um, 8x8 = 64, 9x7 = 63...

Quite...

[TR]SweetSpotOz · 12 Jun 2008 at 23:13

p4radox · 12 Jun 2008 at 23:14

markyp23 said:
It's blatantly not a rectangle (or square for the first one).

What do you mean?

JIM_BOB7813 · 12 Jun 2008 at 23:15

It only works when you multiply/divide by the same factor, not when you add/take away from each.
2x4 isn't the same as 1x5 (subtract 1 from the first, add 1 to the other)
2x4 is the same as 1x8 (half one double the other)

Ricochet J · 12 Jun 2008 at 23:15

p4radox said:
What do you mean?

You're talking about circumferences and you're calculating area's of rectangles.

daz · 12 Jun 2008 at 23:15

Ok seriously, stop playing now.

Perimeter = 2 (length + width)

Area = length x width

daz · 12 Jun 2008 at 23:16

Ricochet J said:
You're talking about circumferences and you're calculating area's of rectangles.

Who's talking about circumference?

Not sure why people are talking about ovals and such either.

[TR]SweetSpotOz · 12 Jun 2008 at 23:17

Ricochet J · 12 Jun 2008 at 23:17

daz said:
Who's talking about circumference?

Yermum.

p4radox · 12 Jun 2008 at 23:17

Ricochet J said:
You're talking about circumferences and you're calculating area's of rectangles.

I didn't mention circumferences...

I just thought that it was a simple enough multiplication.

daz · 12 Jun 2008 at 23:17

Ricochet J said:
Yermum.

Ah, I guessed that the OP meant perimeter. Considering his grasp of maths, it's not surprising his terminology was out.

daz · 12 Jun 2008 at 23:18

Ricochet J said:
Yermum.

I think you'll find it was your mum