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Trigo inequality (Posted on 2014-12-11) Difficulty: 3 of 5
Let c be the Champernowne's constant, or c=0.123456789101112131415161718192021....

Show, without calculator aid, that
sin(c) + cos(c) + tan(c) > 10c

No Solution Yet Submitted by Danish Ahmed Khan    
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Some Thoughts re: solution | Comment 5 of 11 |
(In reply to solution by Ady TZIDON)

But an error still occurs at

sin(c)+cos(c)+ tan(c)>1+2c-(.5*c^2+2(c^3)/6)=1+2c-d

d is a positive value ,

so sin(c)+cos(c)+ tan(c)>1+2c

You have said that after subtracting a positive value from the RHS, that the LHS exceeds it. But you're using merely that fact to claim that even before you've subtracted the positive value from the RHS, that even then the LHS exceeded it.  That is not necessarily the case.

  Posted by Charlie on 2014-12-13 08:07:18
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