Comments on: Math Brain Teaser: Concentric Shapes or The Unkindest Cut of All, Part 2 of 2 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/ Brain Fitness and Cognitive Health news Fri, 20 Nov 2009 11:59:27 -0500 http://wordpress.org/?v=2.8.4 hourly 1 By: Egon_Freeman http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-203285 Egon_Freeman Thu, 06 Nov 2008 19:48:36 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-203285 I arrived at this conclusion through "grazing both squares in exactly 4 points" - corners of the smaller one, and the 'centers' of walls of the bigger one. Primarily through "spatial reasoning", rotated the inner square, and arrived at a point stated in the previous puzzle. 10 seconds. Once again, change it to "Easy" (esp. if someone solved, or at least read, the previous puzzle). I arrived at this conclusion through “grazing both squares in exactly 4 points” – corners of the smaller one, and the ‘centers’ of walls of the bigger one.

Primarily through “spatial reasoning”, rotated the inner square, and arrived at a point stated in the previous puzzle.

10 seconds. Once again, change it to “Easy” (esp. if someone solved, or at least read, the previous puzzle).

]]> By: easyas123 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-183581 easyas123 Thu, 04 Sep 2008 09:40:25 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-183581 quite easy, i like those kind of problems quite easy, i like those kind of problems

]]> By: whoop http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-159523 whoop Thu, 15 May 2008 01:40:17 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-159523 Its easy if you realize that the radius of the circle is both half the diagonal of the smaller square and half the side value of the larger square. Its easy if you realize that the radius of the circle is both half the diagonal of the smaller square and half the side value of the larger square.

]]> By: Peter Cooper http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-159304 Peter Cooper Wed, 14 May 2008 02:30:17 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-159304 I did it by saying that the outer square's area is x^2. The internal square's diagonal length must be x, so its perpendicular length must be the square root of x^2 / 2 (Pythagorus). Squaring that undoes the square root, so you get x^2 compared to x^2 / 2. Factoring down the x^2 to 1, we get 1/0.5.. or 2/1. I did it by saying that the outer square’s area is x^2. The internal square’s diagonal length must be x, so its perpendicular length must be the square root of x^2 / 2 (Pythagorus). Squaring that undoes the square root, so you get x^2 compared to x^2 / 2. Factoring down the x^2 to 1, we get 1/0.5.. or 2/1.

]]> By: » Brain Teasers and Games for adults, with a neuroscience angle: our Top 50    « Brain Fitness Revolution at SharpBrains      http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-80777 » Brain Teasers and Games for adults, with a neuroscience angle: our Top 50    « Brain Fitness Revolution at SharpBrains      Tue, 16 Oct 2007 17:46:33 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-80777 [...] 47. For geniuses: Concentric Shapes or The Unkindest Cut of All, Part 2 of 2. [...] [...] 47. For geniuses: Concentric Shapes or The Unkindest Cut of All, Part 2 of 2. [...]

]]> By: T ROY http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-57993 T ROY Sun, 15 Jul 2007 06:17:57 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-57993 THIS WAS FUN (I GOT THEM ALL OF COURSE EXCEPT THE VEGETABLES. FRUIT OF A PINE TREE (SEEDS ON OUTSIDE) THIS WAS FUN (I GOT THEM ALL OF COURSE EXCEPT THE VEGETABLES.

FRUIT OF A PINE TREE
(SEEDS ON OUTSIDE)

]]> By: Caroline http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-42199 Caroline Mon, 14 May 2007 06:30:18 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-42199 I think you created a more difficult brain teaser! Nice solution. Now we just need to strengthen those reading attention skills! ;-) (sorry if the picture was misleading - I just like the picture and thought it went with the theme, if not the specifics) I think you created a more difficult brain teaser! Nice solution. Now we just need to strengthen those reading attention skills! ;-) (sorry if the picture was misleading – I just like the picture and thought it went with the theme, if not the specifics)

]]> By: stefan http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/comment-page-1/#comment-42091 stefan Sun, 13 May 2007 16:18:30 +0000 http://www.sharpbrains.com/blog/2007/05/08/math-brain-teaser-concentric-shapes-or-the-unkindest-cut-of-all-part-2-of-2/#comment-42091 I mis-read the instructions to be the opposite: an outer circle, a square inside that and another circle inside the square, and calc the area difference between the *circles*. Perhaps I looked at the picture instead of read the instructions! Anyway, I solved it with trig (draw a right triangle with one point in the center, another to a corner of the square and another to a near side of the square). The area of each circle can be derived from the length of the shorter side. Interestingly, it comes out to the same answer: the outer circle is twice the area of the smaller one! I mis-read the instructions to be the opposite: an outer circle, a square inside that and another circle inside the square, and calc the area difference between the *circles*. Perhaps I looked at the picture instead of read the instructions!

Anyway, I solved it with trig (draw a right triangle with one point in the center, another to a corner of the square and another to a near side of the square). The area of each circle can be derived from the length of the shorter side.

Interestingly, it comes out to the same answer: the outer circle is twice the area of the smaller one!

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