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MATHS HELP: Where am I going wrong in this CAST diagram?

The answer is meant to be 12.1 and 124.3 so I went terribly wrong somewhere, but I just don't know where..

Original post by creativebuzz
The answer is meant to be 12.1 and 124.3 so I went terribly wrong somewhere, but I just don't know where..



You've used the diagram at the wrong time. Arccos(3/root29)=56.15 and -56.15.
Original post by Chlorophile
You've used the diagram at the wrong time. Arccos(3/root29)=56.15 and -56.15.


Why is it both 56.15 and -56.15?
Original post by creativebuzz
Why is it both 56.15 and -56.15?


cos(56.15)=cos(-56.15)
Original post by Chlorophile
cos(56.15)=cos(-56.15)


Ah okay, so I should only and always do that when working with cosine?
Original post by creativebuzz
Ah okay, so I should only and always do that when working with cosine?


Well that's what the cosine graph looks like, it's symmetrical around the y axis. For sin, for instance, sin(x)=-sin(-x)

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