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r/Geometry

🔥 Hot ▲ 34.6k r/Geometry+3 crossposts

Adding the extra square

Source: PuzzleHive

u/Muskattt — 8 days ago
▲ 2 r/Geometry

Did we discover all possible shapes, or are we just blind to something obvious that flees from our eyes?

So, I've been thinking about all the shapes humanity has invented, and they are all basically made up of curves and straight lines. Is there a possibility that we aren't noticing a particular new shape because it simply doesn't fit into our imagination, even if it is composed mainly of straight lines? Do you have any literature recommendations, etc.?

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u/Ok_Trifle1381 — 5 days ago
▲ 199 r/Geometry+5 crossposts

Visualizing Polar Roses: How changing k-values transforms r = cos(kθ)

u/USedona — 9 days ago
▲ 3 r/Geometry+1 crossposts

What angle do I cut this middle slant piece of wood?

I'm trying to create some wooden letters for my daughter and I'm struggling to understand how to cut the angled slant in the letter "Z". I'm using pieces of wood that are 1.5" wide. I want the overall letter height to be 7", overall width 5.5", so the middle slant is made up of a 1.5" wide board, cut at angles, to fit within a 4" tall, 5.5" wide area. Wanting the edges of the slant to meet the edges of the top and bottom pieces. I feel like I was decent in geometry, but can't figure out how to approach this. I guess I could just lay things down and measure/cut, but I'm determined to figure out the math and cut list before I start.

u/skotmerfie — 10 days ago
▲ 4 r/Geometry+1 crossposts

is this game or not? geometry td experiment

needs a ton of work but started givin fun feeling

u/sinanata — 10 days ago
▲ 11 r/Geometry+1 crossposts

Why 2\pi r?

Hi everyone I hope you are having a great day. I want to share one of my aops post. Hope you enjoy!

u/ismetinonu__ — 11 days ago
▲ 6 r/Geometry+1 crossposts

Trying to understand the maths of a church window

Hello everyone !
Currently, I am drawing a lot of churches (and other religious buildings, mostly european and christian) windows and arcades for fun.
I came upon the following "window" (see image attached) (it's from Mosteiro dos Jerónimos near Lisboa in Portugal) and I was wondering, how can we calculate the diameter of the small circle at the top, knowing the diameter of the big circle that hosts it ?
I could not find myself, so I asked my friend who is math savvy and they helped me find a way to calculate it.

If you look at the graph they made (basically the window is the space between C, B and G, and the small circle is the circle of center I and of diameter GI), I will explain how we did it.
We consider the square triangle FCI.
According the Pythagore, we know that
FC² + IF² = CI²
Let's write the big circle's radius d (which is FC), and the small circle radius x (which is IG).
We know that FC = d, IF = d - x, and CI = d + x
So we have the following expression
d² + (d - x)² = (d + x)²
d² + d² - 2*d*x + x² = d² + 2*d*x + x²
d² = 4*d*x
d/4 = x.
So there is a simple 4 factor between the two diameters !

I hope you'll find it interesting. bye bye

u/Vishwas_ — 11 days ago
▲ 2 r/Geometry

Does anyone know what I did wrong here?

I sent my professor CAD position drawing so that he could review it and this is what he answered for position 1. (PS I'm located in europe so we're using european standards)

Position 1- lines of change in the cross-section of the interior of the object?

Here's a photo of my drawing and how my position looks like.

Any help would be useful

u/lapsus_mentis — 12 days ago