4
votes
4
votes
Accepted
8x8 Grid with no parallels
I'm using a $9 \times 9$ matrix, with $1$ if there is a point and $0$ otherwise.
- 7,429
3
votes
How high does the ladder reach up the wall?
Let h,w be the height and width of the triangle formed by the ladder with the wall and the ground.
First let us divide through with d: $H:=h/d, W:=w/d, L:=l/d, D:=d/d=1$
Then
$L^2=H^2+W^2$ (1).
...
- 11.6k
2
votes
Accepted
Two triangles in a circle
The answer is intuitively clear:
Formal proof is also not all that difficult:
- 11.6k
2
votes
A donut, a piece of string and a pair of spectacles
I also believe your puzzle is impossible.
Let's simplify the puzzle a bit more. If you rotate the left red (elongated) torus half a turn and merge the holes of the red tori you get something like ...
- 19.3k
1
vote
Two triangles in a circle
Cut a square out of the circle. Divide it in the diagonal to make two equal triangles.
Area of circle:
$\pi r^{2}$
Diagonal of square:
Side of square:
Area of square:
Part of square in the circle:...
- 8,828
1
vote
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