"Triangle ABC has Â = 58°, AB = 10cm and AC = 5.1 cm. Find angle C correct to the nearest thenth of a degree using the sine rule."

This is easy with the cosine rule, but I don't know how to do it with only the sine rule...(Headbang)

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- October 16th 2009, 02:25 PMkarldiesenHelp with cosine rule!
"Triangle ABC has Â = 58°, AB = 10cm and AC = 5.1 cm. Find angle C correct to the nearest thenth of a degree using the sine rule."

This is easy with the cosine rule, but I don't know how to do it with only the sine rule...(Headbang) - October 16th 2009, 03:18 PMstapel
I would guess that "using the sine rule" is a typo, since the Sine Rule does not apply to this situation: you don't have an angle measure and the length of the opposite side. (Wink)

- October 16th 2009, 06:29 PMHallsofIvy
Specifically, since you are told the measure of angle A, you would have to know the length of BC to use the sine law.

- October 17th 2009, 02:19 AMkarldiesen
Yes, but the confusing part is that the question is actually divided into several parts. The first states to use the sine rule. The second, to use the cosine rule.

But hopefully it is just a typo...