Sines and Cosines

W

WTF?

Junior Member
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Sep 16, 2005
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Hello, and pardon my ignorance, but I have a bit of trouble doing this one (though I may just be stupid)

For what value(s) of x such that 0<x<360 does sin28 = cos x?

Do I subtract 360-28?!!
 
Hint: \(\displaystyle sin(x) = cos(\frac{\pi}{2}-x)\)
 
Hello, and pardon my ignorance, but I have a bit of trouble doing this one (though I may just be stupid)

For what value(s) of x such that 0<x<360 does sin28 = cos x?

Do I subtract 360-28?!!

-----------------

You have to use the fact that sin A = cos (90 - A)

So: sin 28 = cos (90-28) = cos 62

Also, cos B = cos (360 - B) , so cos 62 = cos (360 - 62) = cos 298

So putting it all together: sin 28 = cos 62 = cos 298

Hope that helps...

Steve
 
Second hint
pi/2=90°
cos(x)=cos(-x)=cos(-x+360)
---------------
Gene
 
ah, thanks for the help, I fully get that part now.

However, I have another problem that I don't understand.

How do I find the period?

And what does it mean by how the "values" of the function change? for part b. I presume it goes from -1 to 1, right?
 
The period is the "distance" before The curve repeats.
You might add "constantly increasing"

P.S. New problems in a new topic are more likely to get quick replies.
 
Nope, that isn't repeating. Cos(x)=cos(x+360°)
That's repeating!
The period is 360°

Yes, sine/cosine = tangent.
 
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