Question

Can anyone explain law of sines and law of cosines?

Answer 1

In a standard triangle ABC:

The Sine Law tells us that:

`a/sinA = b/sinB =c/sinC`

The Cosine Law tells us that:

`a^2 = b^2 + c^2 - 2bc cos A`
`b^2 = a^2 + c^2 - 2ac cos B`
`c^2 = a^2 + b^2 - 2ac cos C`

In the case that `A,B` or `C=90^o` the cosine rule is equivalent to Pythagoras's Theorem: