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Little explorations with HP calculators (no Prime)
05-22-2018, 03:03 AM
Post: #314
RE: Little explorations with HP calculators (no Prime)
(05-06-2018 06:13 AM)RMollov Wrote:  
(03-27-2017 07:39 PM)Gerson W. Barbosa Wrote:  Let's divide one of the right-triangles into four right-triangles (two with sides lengths equal to r and x and two with side lengths r and 1-x) and a square with side r. Then it's area is

S = r*x + r(1-x) + r^2

S = r^2 + r

The area of the larger square, witch we know is equal to 1, is the sum of the areas of these four right-triangles plus the area of the smaller square in the center, with side 2*r:

S = 4(r^2 + r) + (2*r)^2 = 1


8*r^2 + 4*r - 1 = 0

Here I am tempted to just take my wp34s and do 8 ENTER 4 ENTER 1 +/- SLVQ and get a valid numerical answer for the quadratic equation, but I decide to go through a few more steps by hand and get the exact answer:

r = (sqrt(3) - 1)/4

Would you show those steps here? I stopped before them thinking that's enough...

Sorry for the late reply! I stopped following this thread since page 8 or 9, so I’ve completely missed your request.
The next steps are simply the manual solution of the second-degree equation using Baskhara’s formula:

r = (-4 + sqrt(4^2 - 4*8*(-1)))/(2*8)
r = (-4 + sqrt(48))/16
r = (sqrt(3) - 1)/4

Pier has provided a drawing that illustrates the solution.

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RE: Little explorations with HP calculators (no Prime) - Gerson W. Barbosa - 05-22-2018 03:03 AM

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