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Edexcel C3 Help

Hi, you know the questions where it says show that so and so can be in the form RCos/Sin (theta +- Alpha). For those questions are you allowed to straight up work R and alpha out using their formulaes or do you need to prove it by expanding it and cancelling then comparing etc. On mark schemes I have seen the marks come from the formulae but I need to make sure I am not practicing wrong
Original post by mahmzo
Hi, you know the questions where it says show that so and so can be in the form RCos/Sin (theta +- Alpha). For those questions are you allowed to straight up work R and alpha out using their formulaes or do you need to prove it by expanding it and cancelling then comparing etc. On mark schemes I have seen the marks come from the formulae but I need to make sure I am not practicing wrong


Stick with the level of detail offered in the mark scheme.
There was one mark scheme which said in small writing, that the expansion must be shown, so to be sure I would stick with the expansion. It would also help you to avoid mistakes when Asinx and Bcosx are switched around.

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