need help on solving the end of a calculus problem

[macman2790]

I'm using rolle's theorem which doesnt really matter.

All i need to know is how to solve this:

0 = 2*pi*cos(2*pi*x)

I know it deals with an inverse cosine but i dont know how to manipulate it.

thanks.

 

[plinden]

I'm using rolle's theorem which doesnt really matter.

All i need to know is how to solve this:

0 = 2*pi*cos(2*pi*x)

I know it deals with an inverse cosine but i dont know how to manipulate it.

thanks.

I'm not going to tell you the answer, but you don't need to worry about the 2*pi multiplier, meaning you're looking for a value of x where cos(2*pi*x) = 0

 

[P-Worm]

Instead of using an inverse cosine (which you still could, it would work), just think to yourself "What value does 2*Pi*x need to be to make the cosine of it equal to zero?"

P-Worm

 

[GFLPraxis]

I'm using rolle's theorem which doesnt really matter.

All i need to know is how to solve this:

0 = 2*pi*cos(2*pi*x)

I know it deals with an inverse cosine but i dont know how to manipulate it.

thanks.

You've got three elements being multiplied here; 2, pi, and cos(2*pi*x).
For the whole thing to be equal to zero, one of those three elements has to be zero, right? (since anything multiplied by zero is zero).

2 can never be 0. Pi can never be zero. You know that 0 = cos(2*pi*x).

What does X have to be for that to be zero?

 

[siurpeeman]

Instead of using an inverse cosine (which you still could, it would work), just think to yourself "What value does 2*Pi*x need to be to make the cosine of it equal to zero?"

P-Worm

or you could ask where cosine is equal to zero on the unit circle.

 

[cycocelica]

The answer is clearly dog.

Trust me.

 

[siurpeeman]

the x coordinate on the unit circle is a representation of cosine.

 

[NightFlight]

Oh sweet lord I hated calc.

This makes my head hurt even just trying to remember.

 

[swiftaw]

Am I the only one who is confused about why this is referred to as a calculus problem?

Algebra problem, yes. Trigonometry question, yes. Not sure there is any calculus here though.

Edit: Re-reading the OP, I guess it was a calculus problem that yielded the final equation to be solved.

cos(Y) = 0 when Y is an odd multiple of pi/2 that is when Y = (2i - 1)*pi/2 where i is any integer.

thus in your problem cos(2*pi*x) = 0, x = (2i-1)/4 where i is any integer

 

[BurtonCCC]

This is a pretty standard answer:

Daniel.

 

[iSaint]

The answer is clearly dog.

Trust me.

I concur.

 

[Lunja]

I concur.

Nope, the answer's 42. It's the question that's wrong

 

[mkrishnan]

Am I the only one who is confused about why this is referred to as a calculus problem?

Clearly you are confused, but not as confused as the person with the dog.

I'm guessing the OP had to solve this as part of a calculus problem. Of course this aspect is pretty purely trig.

 

[Abstract]

How can you be doing calculus when you can't solve a very fundamental trigonometry problem?

 

[mkrishnan]

How can you be doing calculus when you can't solve a very fundamental trigonometry problem?

No one said anything about doing calculus well.