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# C2 trigonometry question Watch

1. I've got this:

If sin x = p, where x is an acute angle, find in terms of p the values of:
sin (180º - x), 2sin (180º + x), sin (540º - x), etc.

And also:
If cos y = q, where y is an acute angle, find in terms of q the values of:
cos (pi - y), 3 - 2cos (pi + y), cos (2pi - y), etc.

How do I do this?
I've got my exam in three weeks and don't really know how to do this.

Cheers!
2. you have done the CAST diagram?

ie the diagram with the quadrants where sin is +ve cos +ve sin is +ve cos is-ve
sin is -ve cos -ve and sin -ve cos +ve

so for example sin (360-x) means im in the quadrant where sin x is -ve
then sin(360-x)=-sin(x)=-p
3. I don't think mixing radians and degrees is a good idea.
If you're unsure, you can always do a quick sketch of the sin/cos/tan graph to find other solutions.

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Updated: December 20, 2010
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