Year 12s: what will be the first way you research your future options? >>

Graphing Sin and Tan

I'm having a hard time on what to do one this question

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I think the question is meant to be vague so you can make assumptions. However, I don't know where to start :s-smilie:

Reply 1

brianeverit

Original post by jojo55

I'm having a hard time on what to do one this question

.

I think the question is meant to be vague so you can make assumptions. However, I don't know where to start :s-smilie:

Start by answering the questions, i.e. where does it change direction etc,

Reply 2

jojo55

Original post by brianeverit

Start by answering the questions, i.e. where does it change direction etc,

Thanks for the reply.

So I'd say the projection of point p changes direction when P is at (0,1) and at (0, -1). That is if P is moving anti clockwise.

Reply 3

brianeverit

Original post by jojo55

Thanks for the reply.

So I'd say the projection of point p changes direction when P is at (0,1) and at (0, -1). That is if P is moving anti clockwise.

That's correct. Then, where does it appear to be moving fastest?
Is this the who;e question or are you being asked to draw the graphs?
If you are then you should be able to sketch a graph for the motion of the point along the y axis from your answers.

Reply 4

jojo55

Original post by brianeverit

Thanks, that is the whole question. I can't see where it appears to be moving fastest. How would I go about that?

Reply 5

brianeverit

Original post by jojo55

Thanks, that is the whole question. I can't see where it appears to be moving fastest. How would I go about that?

Just imagine the point moving round the circle at a steady speed. Can you then imagine how the projection on the y axis is moving?

Reply 6

jojo55

Original post by brianeverit

Just imagine the point moving round the circle at a steady speed. Can you then imagine how the projection on the y axis is moving?

The projection will move slower when the point is nearer the top, as it is more level with the y-axis. As it reaches the x-axis, the circle slopes more and makes the y-axis projection move faster.

This crude diagram may explain it better projection pottery.JPG