Hearted Youtube comments on Mathologer (@Mathologer) channel.
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
This is one of the many things I enjoy about traditional geometric patchwork design quilt patterns , (like Flying Geese, Irish Chain, Feathered Star, Grandmother's Flower Basket, Disappearing 9-patch,
Bear's Paw, Log Cabin and all it's variations, Pinwheels, etc.) with 1/2 square or equilateral triangles, rectangles, squares, etc. and shuffling them around to create different patterns. Now I have a name for them, and may design quilt patterns with the names of Pythagoras or Trithagoros, or the long ago Chinese mathematician's name! Great visual explorations of these relationships, thank you. (of course I enjoy even more, the random sewing together of odd shaped and sized pieces, called, "crumb quilting"! lol)
(see also, the 'golden ratio' seen so much in nature and used from antiquity in architecture to produce unconsciously, naturally pleasing, building facades.)
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
For the puzzle at 11:37, I was too tired yesterday to get it, but now that I had time today I gave it another shot.
My square was defined as:
┌──┬──┐ I defined the layout of any pythag.. triple as:.
│B1│B2│ X^2 + Y^2 = Z^2 .
├──┼──┤ .
│B4│B3│ .
└──┴──┘ .
I started out pretty standard with the main three equations of:
B1*B4 = X
2*B2*B3 = Y
B1*B3 + B2*B4 = Z
I also included these:
B1 + B2 = B3
B2 + B3 = B4
To define the innercircle, I used r_i to denote its radius. The equation is then:
r_i = B1*B2
I started by creating an equation to find r_i. To do this, I used the slope of the hypotenuse (Y/X) to solve for an angle, divide it by two, and convert it back to a slope. This gives a slope which bisects the angle XZ. The equation is:
y=tan(1/2 * arctan(Y/X)) * (x+X) (my origin is placed at the corner XY so x+X places the lines origin at the corner XZ)
Using trig identities, namley half angle identity and inverse trig identities, I could simplify the expression:
tan(1/2 * arctan(Y/X)) =>
(sin(arctan(Y/X))) / (1 + cos(arctan(Y/X))) =>
(((Y/X)/sqrt[1 + (Y/X)^2]) / (1 + (1/sqrt[1 + (Y/X)^2])) =>
(Y/X) / (sqrt[1 + (Y/X)^2] + 1) =>
Y / (sqrt[X^2 + Y^2] + X)
This means that the equation is:
y = (Y / (sqrt[X^2 + Y^2] + X))(x+X)
Which is our equation for the first bisector line.
Since the angle XY is 90°, it has a bisector with a slope of -1. This results in the equations:
y=-x
Setting them equal to find the centre of the incircle results in a simplified equation of:
x = -XY / (X + Y + sqrt[X^2 + Y^2]))
Since X^2 + Y^2 = Z^2, this becomes:
x = -XY / (X + Y + Z))
OR:
r_i = (XY) / (X+Y+Z)
Plugging in the values, we get:
r_i = 36
since r_i = B1*B2 = 36, this means B1 = 36/B2.
plugging into the equation: B1 + B2 = B3 yields:
36/B2 + B2 = B3 =>
36 = B2*B3 - B2^2
using Y = 2*B2*B3 = 104, we know B2*B3 = 52.
36 = 52 - B2^2 =>
B2^2 = 52-36 =>
B2 = 4.
So, using B2*B3 = 52 we find:
B3 = 13
Since B1 + B2 = B3:
B1 + 4 = 13
Or:
B1 = 9
Since B2 + B3 = B4:
4 + 13 = B4
Or:
B4 = 17
To Conclude, my guess as to the numbers in the square are:
┌──┬──┐
│ 9│ 4│
├──┼──┤
│17│13│
└──┴──┘
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4
-
4