Raj Raizada
@rajraizada.bsky.social
Math + coding educator in NYC. Used to be university prof doing neuroscience, far happier in math ed. I enjoy making math games, in Desmos and also p5play. rajeevraizada.github.io
I'll try making some simple @desmos.com art with my students today. The only "math" part of this is the geometric dilation with a list of scale factors: the rest is just drawing with the Geometry polygon tool. So, mostly fun, but some learning too!
www.desmos.com/geometry/why...
#iTeachMath #MathSky
www.desmos.com/geometry/why...
#iTeachMath #MathSky
October 31, 2025 at 11:13 AM
I'll try making some simple @desmos.com art with my students today. The only "math" part of this is the geometric dilation with a list of scale factors: the rest is just drawing with the Geometry polygon tool. So, mostly fun, but some learning too!
www.desmos.com/geometry/why...
#iTeachMath #MathSky
www.desmos.com/geometry/why...
#iTeachMath #MathSky
Here's a Halloween-themed @desmos.com geometry activity, in case anyone is looking for one. Task: transform the black witch's hat onto the orange one. The first few screens use constructions, and the rest use coordinate transformations.
classroom.amplify.com/activity/690...
#iTeachMath #MathSky
classroom.amplify.com/activity/690...
#iTeachMath #MathSky
October 30, 2025 at 2:58 PM
Here's a Halloween-themed @desmos.com geometry activity, in case anyone is looking for one. Task: transform the black witch's hat onto the orange one. The first few screens use constructions, and the rest use coordinate transformations.
classroom.amplify.com/activity/690...
#iTeachMath #MathSky
classroom.amplify.com/activity/690...
#iTeachMath #MathSky
The new surface-colouring option in @desmos.com 3D allows a cute way of visualizing conic sections.
www.desmos.com/3d/fiv5gnltdl
(The option to have translucent surfaces doesn't save with the graph itself, so needs to be re-toggled on. It's important for seeing the full curves)
#MathSky #iTeachMath
www.desmos.com/3d/fiv5gnltdl
(The option to have translucent surfaces doesn't save with the graph itself, so needs to be re-toggled on. It's important for seeing the full curves)
#MathSky #iTeachMath
October 29, 2025 at 3:38 PM
The new surface-colouring option in @desmos.com 3D allows a cute way of visualizing conic sections.
www.desmos.com/3d/fiv5gnltdl
(The option to have translucent surfaces doesn't save with the graph itself, so needs to be re-toggled on. It's important for seeing the full curves)
#MathSky #iTeachMath
www.desmos.com/3d/fiv5gnltdl
(The option to have translucent surfaces doesn't save with the graph itself, so needs to be re-toggled on. It's important for seeing the full curves)
#MathSky #iTeachMath
I saw this poster in NYC, and was struck by how it (unintentionally) embodies a key tension in the philosophy of free will. We tend to be determinist when forgiving people we feel sympathy for, and libertarian when criticizing views that we dislike.
October 26, 2025 at 2:31 PM
I saw this poster in NYC, and was struck by how it (unintentionally) embodies a key tension in the philosophy of free will. We tend to be determinist when forgiving people we feel sympathy for, and libertarian when criticizing views that we dislike.
October 25, 2025 at 3:35 PM
Complex function domain-colouring of roots of unity, in @desmos.com
Here's the graph:
www.desmos.com/3d/hadt9rebbe
They recently enabled colouring a surface using functions, so far only in 3D grapher. Side-effect: allows complex domain colouring, using 3D tool as a 2D one! #iTeachMath #MathSky
Here's the graph:
www.desmos.com/3d/hadt9rebbe
They recently enabled colouring a surface using functions, so far only in 3D grapher. Side-effect: allows complex domain colouring, using 3D tool as a 2D one! #iTeachMath #MathSky
October 22, 2025 at 9:50 AM
Complex function domain-colouring of roots of unity, in @desmos.com
Here's the graph:
www.desmos.com/3d/hadt9rebbe
They recently enabled colouring a surface using functions, so far only in 3D grapher. Side-effect: allows complex domain colouring, using 3D tool as a 2D one! #iTeachMath #MathSky
Here's the graph:
www.desmos.com/3d/hadt9rebbe
They recently enabled colouring a surface using functions, so far only in 3D grapher. Side-effect: allows complex domain colouring, using 3D tool as a 2D one! #iTeachMath #MathSky
Timeline palate-cleanser: some pretty geometry in @desmos.com
www.desmos.com/geometry/wgp...
#iTeachMath #MathSky
www.desmos.com/geometry/wgp...
#iTeachMath #MathSky
October 15, 2025 at 7:29 PM
Timeline palate-cleanser: some pretty geometry in @desmos.com
www.desmos.com/geometry/wgp...
#iTeachMath #MathSky
www.desmos.com/geometry/wgp...
#iTeachMath #MathSky
October 9, 2025 at 4:21 PM
I think my geometry students will enjoy making an infinite zoom effect, using the dilation tool in @desmos.com Geometry. Here's an initial attempt. Don't stare at it for too long! 😀
www.desmos.com/geometry/x46...
#iTeachMath
www.desmos.com/geometry/x46...
#iTeachMath
October 1, 2025 at 10:41 AM
I think my geometry students will enjoy making an infinite zoom effect, using the dilation tool in @desmos.com Geometry. Here's an initial attempt. Don't stare at it for too long! 😀
www.desmos.com/geometry/x46...
#iTeachMath
www.desmos.com/geometry/x46...
#iTeachMath
September 28, 2025 at 1:46 PM
I googled around a bit and found this website, which makes things very easy: infuse-qr.com
Does this QR code work for your phone? It does with mine. It should take you to my website.
Does this QR code work for your phone? It does with mine. It should take you to my website.
September 28, 2025 at 12:38 PM
I googled around a bit and found this website, which makes things very easy: infuse-qr.com
Does this QR code work for your phone? It does with mine. It should take you to my website.
Does this QR code work for your phone? It does with mine. It should take you to my website.
Is this a new piece of Kenny Scharf graffiti on W 57th St? I walked past it this morning and don’t recall seeing it before.
September 22, 2025 at 12:21 PM
Is this a new piece of Kenny Scharf graffiti on W 57th St? I walked past it this morning and don’t recall seeing it before.
Here is a @desmos.com activity about the symmetry-preserving transformations of a square, inspired by my colleague Tom Jameson.
classroom.amplify.com/activity/68c...
For a really great intro to how this relates to group theory, see this by @stevenstrogatz.com archive.nytimes.com/opinionator....
classroom.amplify.com/activity/68c...
For a really great intro to how this relates to group theory, see this by @stevenstrogatz.com archive.nytimes.com/opinionator....
September 21, 2025 at 10:02 PM
Here is a @desmos.com activity about the symmetry-preserving transformations of a square, inspired by my colleague Tom Jameson.
classroom.amplify.com/activity/68c...
For a really great intro to how this relates to group theory, see this by @stevenstrogatz.com archive.nytimes.com/opinionator....
classroom.amplify.com/activity/68c...
For a really great intro to how this relates to group theory, see this by @stevenstrogatz.com archive.nytimes.com/opinionator....
Seen at the MoMA Design Store. @momanyc.bsky.social .
It’s a nicely designed light, but it’s not a hexagon! #
It’s a nicely designed light, but it’s not a hexagon! #
August 30, 2025 at 7:15 PM
Seen at the MoMA Design Store. @momanyc.bsky.social .
It’s a nicely designed light, but it’s not a hexagon! #
It’s a nicely designed light, but it’s not a hexagon! #
I found out what it's called: a Brianchon point. The concurrency comes from the main Brianchon's theorem for concurrency in a hexagon of conic tangents: it is a projective dual of Pascal's theorem. If you combine three pairs of the six edges, then you get a triangle.
en.wikipedia.org/wiki/Brianch...
en.wikipedia.org/wiki/Brianch...
August 7, 2025 at 5:07 PM
I found out what it's called: a Brianchon point. The concurrency comes from the main Brianchon's theorem for concurrency in a hexagon of conic tangents: it is a projective dual of Pascal's theorem. If you combine three pairs of the six edges, then you get a triangle.
en.wikipedia.org/wiki/Brianch...
en.wikipedia.org/wiki/Brianch...
Thanks! Here’s an example with a hyperbola. The tangent contact points are orange, and the lines from them to their opposite vertices all meet concurrently at the green point J.
I’m curious about that point, and how to show that the lines are concurrent there.
I’m curious about that point, and how to show that the lines are concurrent there.
August 6, 2025 at 9:00 PM
Thanks! Here’s an example with a hyperbola. The tangent contact points are orange, and the lines from them to their opposite vertices all meet concurrently at the green point J.
I’m curious about that point, and how to show that the lines are concurrent there.
I’m curious about that point, and how to show that the lines are concurrent there.
Example:
Fun to drag the tangent points around and see how the concurrency remains. Try it with hyperbolas and a parabola too. It also works!
Fun to drag the tangent points around and see how the concurrency remains. Try it with hyperbolas and a parabola too. It also works!
August 6, 2025 at 7:39 PM
Example:
Fun to drag the tangent points around and see how the concurrency remains. Try it with hyperbolas and a parabola too. It also works!
Fun to drag the tangent points around and see how the concurrency remains. Try it with hyperbolas and a parabola too. It also works!
@mathtechcoach.bsky.social
I was messing around with conics and ran across your GeoGebra inscribed one. I’m curious: do you happen to know what the point H is called, and how one might prove that the tangent-to-vertex lines are concurrent there? Thanks!
I was messing around with conics and ran across your GeoGebra inscribed one. I’m curious: do you happen to know what the point H is called, and how one might prove that the tangent-to-vertex lines are concurrent there? Thanks!
August 6, 2025 at 6:38 PM
@mathtechcoach.bsky.social
I was messing around with conics and ran across your GeoGebra inscribed one. I’m curious: do you happen to know what the point H is called, and how one might prove that the tangent-to-vertex lines are concurrent there? Thanks!
I was messing around with conics and ran across your GeoGebra inscribed one. I’m curious: do you happen to know what the point H is called, and how one might prove that the tangent-to-vertex lines are concurrent there? Thanks!
Messing around with circle inversions in the complex plane in @desmos.com. #iTeachMath #MathSky
www.desmos.com/calculator/m...
www.desmos.com/calculator/m...
July 10, 2025 at 3:30 PM
Messing around with circle inversions in the complex plane in @desmos.com. #iTeachMath #MathSky
www.desmos.com/calculator/m...
www.desmos.com/calculator/m...
I’m at @unm.edu for a camp my kid is at, and I popped into their meteorite museum. It didn’t look like much, until the amazingly knowledgeable person working there told me more. This fragment of the Murchison meteorite is 7 billion years old: the oldest object on Earth! It contains amino acids!
July 9, 2025 at 9:22 PM
I’m at @unm.edu for a camp my kid is at, and I popped into their meteorite museum. It didn’t look like much, until the amazingly knowledgeable person working there told me more. This fragment of the Murchison meteorite is 7 billion years old: the oldest object on Earth! It contains amino acids!
I was playing around with distance loci in @desmos.com. This one is sort of fun: it looks like the orange blob avoids the black dot by looping around it. #iTeachMath #MathSky
www.desmos.com/calculator/k...
www.desmos.com/calculator/k...
July 2, 2025 at 12:50 PM
I was playing around with distance loci in @desmos.com. This one is sort of fun: it looks like the orange blob avoids the black dot by looping around it. #iTeachMath #MathSky
www.desmos.com/calculator/k...
www.desmos.com/calculator/k...
I was playing around a bit with @desmos.com Geometry, and I stumbled upon yet another rearrangement way of demonstrating the Pythagorean theorem. I don't recall seeing this particular version before, so I figured I'd make an animation of it. #iTeachMath #MathSky
www.desmos.com/geometry/863...
www.desmos.com/geometry/863...
June 17, 2025 at 3:40 PM
I was playing around a bit with @desmos.com Geometry, and I stumbled upon yet another rearrangement way of demonstrating the Pythagorean theorem. I don't recall seeing this particular version before, so I figured I'd make an animation of it. #iTeachMath #MathSky
www.desmos.com/geometry/863...
www.desmos.com/geometry/863...
Despite everything (or maybe because of it?), sometimes it's nice just to play with some silly code. Here's an early-stage game using @q5play.bsky.social for physics, and ml5.js for face-tracking. Your task is to catch fruit with your mouth, but not the germs! 🦠
openprocessing.org/sketch/2664137
openprocessing.org/sketch/2664137
June 4, 2025 at 5:45 PM
Despite everything (or maybe because of it?), sometimes it's nice just to play with some silly code. Here's an early-stage game using @q5play.bsky.social for physics, and ml5.js for face-tracking. Your task is to catch fruit with your mouth, but not the germs! 🦠
openprocessing.org/sketch/2664137
openprocessing.org/sketch/2664137
Aha, excellent point! A very nice use of the fact that the circle centers are the midpoints of the segments linking the vertices to the incenter. Thanks!
Your suggestion prompted me to try repeating that process a couple of times, simply because it would look pretty:
www.desmos.com/geometry/uns...
Your suggestion prompted me to try repeating that process a couple of times, simply because it would look pretty:
www.desmos.com/geometry/uns...
June 2, 2025 at 10:42 AM
Aha, excellent point! A very nice use of the fact that the circle centers are the midpoints of the segments linking the vertices to the incenter. Thanks!
Your suggestion prompted me to try repeating that process a couple of times, simply because it would look pretty:
www.desmos.com/geometry/uns...
Your suggestion prompted me to try repeating that process a couple of times, simply because it would look pretty:
www.desmos.com/geometry/uns...
Is there a name for this arrangement of circles? They pass through the incircle's tangent points and center, and the vertices. Their existence is not at all deep, but they are quite pretty! Is there a name for them, or are they too trivial to have one? #iTeachMath
www.desmos.com/geometry/n0a...
www.desmos.com/geometry/n0a...
June 1, 2025 at 10:14 PM
Is there a name for this arrangement of circles? They pass through the incircle's tangent points and center, and the vertices. Their existence is not at all deep, but they are quite pretty! Is there a name for them, or are they too trivial to have one? #iTeachMath
www.desmos.com/geometry/n0a...
www.desmos.com/geometry/n0a...