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# Trig help! watch

1. The curve C has equation y=cos(x+pi/4), 0<x<2pi###

sketch c.

I haven't a clue how to draw it!
2. Do you know what y=cos(x) looks like?

Do you know what transformation is done for the mapping f(x) -> f(x+k) ?
3. (Original post by dippers)
The curve C has equation y=cos(x+pi/4), 0<x<2pi###

sketch c.

I haven't a clue how to draw it!
Hint:

Given

represents a translation ("shift") by minus a along the x-axis.

So, for your convenience, I'd advise you to first draw cos x and go from there
4. Can you sketch ?

Can you sketch ?
5. (Original post by aznkid66)
Do you know what y=cos(x) looks like?

Do you know what transformation is done for the mapping f(x) -> f(x+k) ?
Yes I know what y=cos(x) looks like, and I don't know the mapping f(x) -> f(x+k)
6. (Original post by Mr M)
Can you sketch ?

Can you sketch ?
No i don't know how to draw either. I know in general what y=cos(x) looks like
7. (Original post by dippers)
No i don't know how to draw either. I know in general what y=cos(x) looks like
Ok.

Sketch and sketch where are two ways of asking you to do the same thing.

It sounds like you need to revise GCSE or Core 1 graph transformations.

is a translation of by k units in the positive x direction.
8. (Original post by dippers)
Yes I know what y=cos(x) looks like, and I don't know the mapping f(x) -> f(x+k)

The graph will move a units to the left, as the values of f(x) will happen a units earlier. Find an online graphing calulator and type in both eqations into it, it will become clearer.
9. You should know that cos(x) from 0 to 2pi has a a maximum at (0,1) and (2pi, 1) and a minimum at (pi,-1)
You should also know it crosses the x axis at (pi/2,0) and (3pi/2,0)

Also, from knowing its period or otherwise, you should be able to draw cos(x) with varying domains.
In addition, you should know how to identify transformations such as translations and stretches, and how they affect the principle axis, amplitude/maxes/mins, period, etc.

For the specific transformation required in this problem, see post #3. Although you should really know all of them.
10. Am I suppose to draw an accurate drawing of it? with the axis labelled?
11. (Original post by dippers)
Am I suppose to draw an accurate drawing of it? with the axis labelled?
Do you know what the word 'sketch' means in mathematics?
12. Lol, didn't know it said sketch.

No, it doesn't have to be super accurate, but you should at least have it be bounded by y=1 and y=-1 and have the period and horizontal shift right so that you can see what's going on.
13. (Original post by aznkid66)
Lol, didn't know it said sketch.

No, it doesn't have to be super accurate, but you should at least have it be bounded by y=1 and y=-1 and have the period and horizontal shift right so that you can see what's going on.
Ok thanks and then it says write down the exact coordinates at which c meets the coordinate axis. How would I do that?
14. (Original post by dippers)
Ok thanks and then it says write down the exact coordinates at which c meets the coordinate axis. How would I do that?
Actually go ahead and do the sketch and it should be obvious.
15. (Original post by Mr M)
Actually go ahead and do the sketch and it should be obvious.
I'm afraid I do not know what I'm doing! I know I have to move the graph to the left but I do not know how to find out the coordinates.
16. If a graph is shifted to the left by pi/4, then each point on the graph, including its x-intercepts, is shifted to the left by pi/4.
17. (Original post by dippers)
I'm afraid I do not know what I'm doing! I know I have to move the graph to the left but I do not know how to find out the coordinates.
You are trying to run before you can walk. You need to address some of the gaps in your knowledge. Do you have a teacher you can speak to about logarithms, graph transformations and graph sketching?

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