Why Does This Logarithmic Trigonometric Equation Equal Zero?

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SUMMARY

The logarithmic trigonometric equation involving the sum of logarithms of tangent functions, specifically {\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} = 0, is proven to equal zero through the properties of logarithms and tangent functions. The solution reveals that tan\ 1^\circ + tan\ 2^\circ + ... + tan\ 89^\circ = 1 and highlights the importance of recognizing that f(a + b + c) \ne f(a) + f(b) + f(c) in general. The discussion also addresses a common error regarding the undefined logarithm at tan 45^\circ.

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  • Understanding of logarithmic identities, specifically log_b(A) + log_b(B) = log_b(AB)
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  • Basic knowledge of the properties of logarithms, including antilogarithms
  • Experience with mathematical proofs and error identification in equations
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Homework Statement
Prove,
##\frac{1}{\log_{tan\ 1^\circ}(2021)} +\frac{1}{\log_{tan\ 2^\circ}(2021)} +\frac{1}{\log_{tan\ 3^\circ}(2021)} +...+\frac{1}{\log_{tan\ 89^\circ}(2021)} = 0 ##
Relevant Equations
-
The attempt at a solution

##

{\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +{\log_{2021}(tan\ 3^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} = 0 \\

Antilog_{2021}[{\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +{\log_{2021}(tan\ 3^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} ] = Antilog_{2021}[0]\\
tan\ 1^\circ + tan\ 2^\circ + tan\ 3^\circ +...+ tan\ 89^\circ = 1\\
arctan(tan\ 1^\circ + tan\ 2^\circ + tan\ 3^\circ +...+ tan\ 89^\circ = 1)\\
1^\circ +2^\circ +3^\circ +...+89^\circ = 45^\circ \\
\frac{89}{2} \times 90^\circ=45^\circ \\
##
Where did I make mistake?
I also want to know How to display a long equation in the same line in MathJax(Ex. 2nd line)
 
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Manasan3010 said:
Problem Statement: Proof,
The above should be Prove.
You prove (verb) a statement to arrive at a proof (noun).
Manasan3010 said:
##\frac{1}{\log_{tan\ 1^\circ}(2021)} +\frac{1}{\log_{tan\ 2^\circ}(2021)} +\frac{1}{\log_{tan\ 3^\circ}(2021)} +...+\frac{1}{\log_{tan\ 89^\circ}(2021)} = 0 ##
Relevant Equations: -

Working

##

{\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +{\log_{2021}(tan\ 3^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} = 0 \\

Antilog_{2021}[{\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +{\log_{2021}(tan\ 3^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} ] = Antilog_{2021}[0]##
The line below has an error.
##f(a + b + c) \ne f(a) + f(b) + f(c)##, in general.
Manasan3010 said:
##tan\ 1^\circ + tan\ 2^\circ + tan\ 3^\circ +...+ tan\ 89^\circ = 1\\
arctan(tan\ 1^\circ + tan\ 2^\circ + tan\ 3^\circ +...+ tan\ 89^\circ = 1)\\
1^\circ +2^\circ +3^\circ +...+89^\circ = 45^\circ \\
\frac{89}{2} \times 90^\circ=45^\circ \\
##
Where did I make mistake?
I also want to know How to display a long equation in the same line in MathJax(Ex. 2nd line)
 
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Mark44 said:
The line below has an error.
f(a+b+c)≠f(a)+f(b)+f(c)f(a+b+c)≠f(a)+f(b)+f(c)f(a + b + c) \ne f(a) + f(b) + f(c), in general.
Which line are you referring to and What should I to get the correct steps?
 
Manasan3010 said:
Which line are you referring to and What should I to get the correct steps?
The second and third lines of your work.
Manasan3010 said:
##Antilog_{2021}[{\log_{2021}(tan\ 1^\circ)} +{\log_{2021}(tan\ 2^\circ)} +{\log_{2021}(tan\ 3^\circ)} +...+{\log_{2021}(tan\ 89^\circ)} ] = Antilog_{2021}[0]##
The line below doesn't follow from the line above.
Manasan3010 said:
##tan\ 1^\circ + tan\ 2^\circ + tan\ 3^\circ +...+ tan\ 89^\circ = 1##
You are in essence saying that ##f(a + b + c) = f(a) + f(b) + f(c)##, which is generally not true.

Start in again with your first line:
##\log_{2021}(\tan 1^\circ) +\log_{2021}(\tan 2^\circ) +\log_{2021}(\tan 3^\circ) +...+\log_{2021}(\tan 89^\circ) = 0##

Use the idea that ##\log_b(A) + \log_b(B) = \log_b(AB)##
 
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I found the solution Thanks.

If anyone looking for solution Then,
tan1 .tan2 .tan3……tan87 .tan88. tan89

tan1 . tan 2 . tan 3 ….. cot3. cot 2. cot 1

tan1.cot1 . tan2.cot2 …..tan44.cot44. tan45

1*1*1*1…….1
 
There's actually an issue with the problem as stated. The middle term of the series would be
$$\frac 1{\log_{\tan 45^\circ}2021},$$ but the logarithm is undefined since there's no power of 1 that's equal to 2021.
 
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