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# Maths Question Transformations - HELP!!! watch

1. When we have Cos(pie/2 - theta), we can represent this as Cos(-theta+pie/2)

I understand that when drawing this graph we will shift cos(x) by pie/2 units to the left, but why is it reflected in the x axis? I thought that because it is Cos(-theta), it would be a y axis reflection, similar to y=f(-x)
2. (Original post by I am Babatunde)
When we have Cos(pie/2 - theta), we can represent this as Cos(-theta+pie/2)

I understand that when drawing this graph we will shift cos(x) by pie/2 units to the left, but why is it reflected in the x axis? I thought that because it is Cos(-theta), it would be a y axis reflection, similar to y=f(-x)
Do you mean and getting there by a transformation?
3. No, sorry if i was a bit unclear.

Just simply representing Cos(pi/2 - theta) graphically, which i rearranged to give cos(theta-pi/2) to make this easier to then do.
4. (Original post by SeanFM)
Do you mean and getting there by a transformation?
Could you kindly assist in talking me through how we represent this graphically?
5. (Original post by I am Babatunde)
Could you kindly assist in talking me through how we represent this graphically?
Draw a graph of cosine. What happens if you graph cosine of -theta, rather than theta? Now draw where the y axis would be for each of those functions
6. (Original post by I am Babatunde)
Could you kindly assist in talking me through how we represent this graphically?
I see, I posted to clarify as I think you've made an unfortunate typo in your OP

I've tried to explain it but had to delete my post as to be honest it would confuse you more. It isn't easy to explain in words if you receive no further replies I will try again (will also have a think about it in the morning..)
7. (Original post by I am Babatunde)
When we have Cos(pie/2 - theta), we can represent this as Cos(-theta+pie/2)

I understand that when drawing this graph we will shift cos(x) by pie/2 units to the left, but why is it reflected in the x axis? I thought that because it is Cos(-theta), it would be a y axis reflection, similar to y=f(-x)
(Original post by I am Babatunde)
No, sorry if i was a bit unclear.

Just simply representing Cos(pi/2 - theta) graphically, which i rearranged to give cos(theta-pi/2) to make this easier to then do.
I don't quite understand what your question is. It is not a translation to the left, it's a translation to the right because and by the even parity of the cosine function so really it's just a translation to the right.

If you want to bring in reflection in the x-axis then you need to be aware that and that sine is an odd function though this is more long winded.

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