More fun in 2016, Part 12

Geometry Level 3

How many complex solutions z z satisfy the equation cos ( z ) = 2016 \cos(z)=2016 ? If you come to the conclusion that there are infinitely many solutions, enter 666.


The answer is 666.

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1 solution

Aareyan Manzoor
Jan 2, 2016

should not take more than a second if you are familiar with this. easy proof is that while z z is a root, so is z ± 2 π z\pm2\pi . so we look at the primary solution z = i ln ( 2016 ± 4064255 ) z = i\ln(2016\pm \sqrt{4064255}) , then all other roots are z = i ln ( 2016 ± 4064255 ) , i ln ( 2016 ± 4064255 ) ± 2 π , i ln ( 2016 ± 4064255 ) ± 4 π . . . . . . . z = i\ln(2016\pm \sqrt{4064255}),i\ln(2016\pm \sqrt{4064255})\pm2\pi,i\ln(2016\pm \sqrt{4064255})\pm4\pi....... hence infinite solutions.

Exactly! (+1) I was posting this because the solution given here is actually wrong. You should tell them!

Otto Bretscher - 5 years, 5 months ago

Don't forget to solve this , my friend ;)

Otto Bretscher - 5 years, 5 months ago

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ok... wow you seem to ave put up alot of problem... but i was at a family function and didnt notice them. let me try to solve them all!

Aareyan Manzoor - 5 years, 5 months ago

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Enjoy! Most of them are probably "too easy" for you ;)

Otto Bretscher - 5 years, 5 months ago

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