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# C2 Trigonometry question Watch

1. Say if they gave this question

Solve cosX=0 for -30 < X < 690*

I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

But is it okay if I do this:
sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
say that cosX graph has period of 360* and then give all the solutions of X.

?? Would I lose marks through this method if it was an exam question?

Thanks
2. (Original post by krisshP)
Say if they gave this question

Solve cosX=0 for -30 < X < 690*

I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

But is it okay if I do this:
sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
say that cosX graph has period of 360* and then give all the solutions of X.

?? Would I lose marks through this method if it was an exam question?

Thanks
You'll be given full credit for any well-structured answer, with ample justification throughout, that gives you all of the solutions
3. (Original post by krisshP)
Say if they gave this question

Solve cosX=0 for -30 < X < 690*

I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

But is it okay if I do this:
sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
say that cosX graph has period of 360* and then give all the solutions of X.

?? Would I lose marks through this method if it was an exam question?

Thanks
It is possible that some examiners would take marks off in C2 but I am not certain about this. For this example though, if
4. (Original post by Indeterminate)
You'll be given full credit for any well-structured answer, with ample justification throughout, that gives you all of the solutions
Thanks

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