[math-fun] ries strikes again. Mathematica answers!
In[69]:= ((1/2 ((-I)^(1 + √2) + I^(1 + √2)) - Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2) + (1/2 ((-I)^(1 + √2) + I^(1 + √2)) + Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2)) // FullSimplify Out[69]= 2 Sin[π 2√2] (How??) --rwg
rwg, apologies for filling your head with all these √2's.
-----Original Message----- From: math-fun [mailto:math-fun-bounces@mailman.xmission.com] On Behalf Of Bill Gosper Sent: Monday, March 27, 2017 8:25 PM To: math-fun@mailman.xmission.com Subject: [math-fun] ries strikes again. Mathematica answers!
In[69]:= ((1/2 ((-I)^(1 + √2) + I^(1 + √2)) - Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2) + (1/2 ((-I)^(1 + √2) + I^(1 + √2)) + Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2)) // FullSimplify
Out[69]= 2 Sin[π 2√2]
(How??) --rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
I took this as a personal challenge. First note that 1/2 ((-I)^(1 + √2) + I^(1 + √2)) = cos(pi(1+sqrt(2))/2) . Let T = pi(1+sqrt(2))/2. Also note that 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2 = (cos T)^2 so that sqrt(-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2) = i sin T . Then the whole expression is (cos T - i sin T)^(1 + sqrt(2)) + (cos T + i sin T)^(1 + sqrt(2)) or exp( -i T (1 + sqrt(2)) + exp( i T (1 + sqrt(2)) = 2 cos(T(1 + sqrt(2))) = 2 cos(pi(1 + sqrt(2))^2 / 2) = 2 cos((pi/2) (3 + 2 sqrt(2)) = 2 cos(3 pi/2 + pi sqrt(2)) = 2 [cos(3 pi/2) cos(pi sqrt(2)) - sin(3 pi/2) sin(pi sqrt(2))] = 2 sin(pi sqrt(2)) Q.E.D. —Dan Bill Gosper wrote (March 27, 2017 at 5:25 pm): ----- In[69]:= ((1/2 ((-I)^(1 + √2) + I^(1 + √2)) - Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2) + (1/2 ((-I)^(1 + √2) + I^(1 + √2)) + Sqrt[-1 + 1/4 ((-I)^(1 + √2) + I^(1 + √2))^2])^(-1 + √2)) // FullSimplify Out[69]= 2 Sin[π 2√2] (How??) -----
participants (3)
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Bill Gosper -
Dan Asimov -
David Wilson