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Domain of a trigonometric function

What is the domain of this trigonometric function?
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Reply 1
Original post by Aaaaaaahgg
What is the domain of this trigonometric function?
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What values do you think x can take?
Reply 2
Original post by mqb2766
What values do you

x is larger than or equal to pie/2
Reply 3
Original post by Aaaaaaahgg
x is larger than or equal to pie/2

Why?
Reply 4
Original post by mqb2766
Why?

Since cosx needs to be less than or equal to 1
Reply 5
Original post by Aaaaaaahgg
Since cosx needs to be less than or equal to 1

I agree with that, so for what values of x does this happen?
Reply 6
Original post by mqb2766
I agree with that, so for what values of x does this happen?

I am not very sure that is why I am asking
Reply 7
Original post by Aaaaaaahgg
I am not very sure that is why I am asking


Can you sketch a cos curve (or a sin curve as they basically the same), when is the value <= 1?

Alternatively, when would
cos(x) > 1

Think about its definition
cos = adjacent/hypotenuse.
can adjacent > hypotenuse or ...?
Reply 8
Original post by mqb2766
Can you sketch a cos curve (or a sin curve as they basically the same), when is the value <= 1?

Alternatively, when would
cos(x) > 1

Think about its definition
cos = adjacent/hypotenuse.
can adjacent > hypotenuse or ...?

Never, so is it an empty set?
Reply 9
Original post by Aaaaaaahgg
Never, so is it an empty set?


Is this for <=1 or >1?

cos(x) <=1
always so the domain is ....
Reply 10
Original post by mqb2766
Is this for <=1 or >1?

cos(x) <=1
always so the domain is ....

All real numbers
Original post by Aaaaaaahgg
All real numbers


Yes.
-1 <= -cos(x) <= 1
so
0 <= 1-cos(x) <= 2
and obviously you can root that.

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