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# sin and cosine rule watch

1. when do I use the sine and cosine rule?
2. (Original post by YasminAKZM)
when do I use the sine and cosine rule?
Sine - when you know an angle and a side which are opposite, as well as one other angle OR side.

Cosine - whenever you know an angle and the two side lengths between it.
3. (Original post by YasminAKZM)
when do I use the sine and cosine rule?
I said nothing before....
what RDK has forgotten is that you will need Cosine for anything where all sides or all angles are labelled and nothing more.
in the case of angles, find the inverted formula (a^2 = ...)
4. (Original post by RDKGames)
Sine - when you know an angle and a side which are opposite, as well as one other angle OR side.

Cosine - whenever you know an angle and the two side lengths between it.
thank you! that's great x
5. (Original post by YasminAKZM)
thank you! that's great x
above post
6. (Original post by ThatsAGoodOne349)
what RDK has forgotten is that you will need Cosine for anything where all sides or all angles are labelled and nothing more.
in the case of angles, find the inverted formula (a^2 = ...)
Wanted to say that but kinda wanted to leave that for the OP to have a dig at.
7. (Original post by RDKGames)
Wanted to say that but kinda wanted to leave that for the OP to have a dig at.
ahh well
I dug into it for them

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