| Title | Description | Geom. Trig. | Number theory | Stats | Algebra | Calc. | Misc. |
| Sneaking up on π with regular polygons | Compute π by fitting regular polygons (triangle, square, hexagon, etc.) to a circle. The more sides your polygons have, the more accurate and precise your computed π becomes. | ✅ |
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| e | Explore the function f(x) = (1 + 1/x)x and see its limit of e. |
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| N-gons and their angles | As the number of sides and hence angles of a regular polygon increases, so do the size of the angles. However, the size of the angles does not increase linearly with the number of angles and cannot grow beyond a certain value. | ✅ |
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| N-gon triangulation | The sum of all (inside) angles of a polygon can be computed by dividing the polygon in triangles. | ✅ |
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| The Collatz conjecture | Take any positive whole number. If it is odd, multiply it by 3 and add 1. If it is even, divide it by 2. Now repeat with the result and keep going. The series of results will always end with ...4, 2, 1 (repeating). |
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| 2D vector rotation | Draw a circle, pick a point on the circle and draw a line from the center of the circle to the point you picked. Now rotate the point you picked along the circle a certain number of degrees (45°, 60°, etc.). What will be the coordinates (x, y) of the rotated point? | ✅ |
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| Sine, cosine and tangent | Explore the basic sine, cosine and tangent functions. | ✅ |
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| Cycloids | Roll a circle around the inside or outside of another circle and follow its trajectory. | ✅ |
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| Chromatic (12-tone) scale of music | Compare and listen to two versions of dividing up the (western) musical scale in 12 tones. |
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| A simple derivative | Early on in calculus we learn that the first derivative of a function is the slope of the line tangent to the function at any point (x, y). On this page you can play with functions of the type f(x) = xn and plot those tangents. |
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| A simple integral | In calculus we learn that we can find the 'area under the curve' of a function by computing the function's integral. On this page you can play with functions of the type f(x) = xn and compute and plot those integrals. |
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| Fibonacci series | The Fibonacci series of numbers starts with the numbers (1, 1). Each next number is the sum of the previous two numbers: 1, 1, 2, 3, 5, 8, 13, 21, 34, etc. | ✅ | ✅ |
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| Triangle circles | Draw a triangle and its incircle and circumcircle (incircle is the largest circle we can fit inside the triangle; circumcircle is the smallest circle into which we can fit the entire triangle). | ✅ |
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| Kaprekar's constants — 6174 and 495 | Take a positive whole number of four digits; move the digits through a few steps and you always end up with the number 6174. Do the same with a three-digit whole positive number and the result will always be 495. |
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| Pick's theorem | If you construct a polygon of which all border points have whole-number coordinates, Pick's theorem states that the area enclosed by that polygon can be computed simply from the number of whole-number points contained by that polygon. | ✅ |
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| The Mandelbrot set | Take a (special) set of complex numbers and submit them to a simple, repeated process. For each of the numbers you picked see if it 'remains in the neighborhood' or 'escapes to infinity.' Paint all the ones that stay in the neighborhood white. |
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| Can you hear me now? | Plot the strengths of signals from two transmitters broadcasting at identical frequencies as their signals are received everywhere around them and marvel at the beauty and complexity of the result. |
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| Sinusoidal Sun | Plot the (noon) angle of the Sun and the length of day for different latitudes on earth over the period of a full year. | ✅ |
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| Ulam spiral of primes | If you plot consecutive numbers in a spiral, prime numbers form spirals of their own. |
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| Equations as matrices | Solve pairs of simple linear equations with just a few matrix operations. |
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| How many paths? | Use simple matrix multiplication to find all the routes (paths) of a certain length between all locations. | ✅ |
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| The Monty Hall puzzle | The Monty Hall puzzle is a famous puzzle that has confused many. Although several solutions for it exist, here we use simulation as a means to explore the two strategies available when playing the puzzle. |
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| The Petersburg paradox | The Petersburg paradox involves the apparent paradox between 50% of something meaning one half of that something, and yet the difference between those 'halves' being quite large. It sometimes confuses those who gamble. |
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| How long before we double or triple? | Play with how long it takes for values to multiply if they grow at a constant rate. |
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| Sum all (whole) numbers from 1 to N | How to quickly sum all (whole) numbers from 1 to N |
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