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# Unable to solve Mechanics problems watch

1. I've noticed on the mark schemes to past papers that when there are angles, they seem to automatically convert any sines into cosines. Would it affect me if I did not change it? Also, concerning vector problems, how can I tell when to provide an answer as a vector or not?
I've noticed on the mark schemes to past papers that when there are angles, they seem to automatically convert any sines into cosines. Would it affect me if I did not change it? Also, concerning vector problems, how can I tell when to provide an answer as a vector or not?
No. I think converting sines to cosines is a bad practice. They should be left as they are. You will not be affected.

As to when your answer should be a vector or not... surely it should be evident from th question? If you work with vectors, your answer is a vector (unless you're finding something like the magnitude of a vector, etc...) otherwise if you're working with scalars, then your answer should be scalars.
3. (Original post by Zacken)
No. I think converting sines to cosines is a bad practice. They should be left as they are. You will not be affected.

As to when your answer should be a vector or not... surely it should be evident from th question? If you work with vectors, your answer is a vector (unless you're finding something like the magnitude of a vector, etc...) otherwise if you're working with scalars, then your answer should be scalars.
Oh, OK, I think I've got it. If you're answering for a vector quantity (e.g. velocity, displacement), then answer in component form (xi + yj); however, if you're answering for a scalar quantity (e.g. speed, distance), then convert it from component form (square root of (x2 + y2))?

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Updated: June 7, 2016
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