How do I know wether to use the sine or cosine rule?
You use the cosine rule when you have been given the length of two sides and an inclusive angle (the angle in between those two lines) or if you have been given the length of three sides.You use the sine rule however if you've been given the length of two sides and a non-inclusive angle or if you've been given the size of two angles and one side.
DP
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