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# quick question, CAST diagram

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1. Hey,

I can't get my head around how they've solved this using the CAST diagram.

cos x =

and x = 150

so in the mark scheme it says clockwise rotation of 150 or anti-clockwise rotation of 210

can someone explain this for me please?
2. (Original post by Ravster)
Hey,

I can't get my head around how they've solved this using the CAST diagram.

cos x =

and x = 150

so in the mark scheme it says clockwise rotation of 150 or anti-clockwise rotation of 210

can someone explain this for me please?
I'm not sure what you mean? There are two solutions, one where and one where ?
3. (Original post by Zacken)
I'm not sure what you mean? There are two solutions, one where and one where ?

The bit where they got 360-150 to get 210. Why did you do this?
4. (Original post by Ravster)

The bit where they got 360-150 to get 210. Why did you do this?
For Cos:
If the first solution is say x(degrees) then the second solution is always 360 (degrees)-x.

(Then the other solutions (if needed) are ±360 degrees the main 2 solutions above.)
5. The reason the above is true is that which is fairly obvious from the graph, but I'm not very familiar with the CAST stuff.

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