You might like to read our page on Trigonometry first!
The triangle identities are equations that are true for all triangles (they don't need to have a right angle). For the identities involving right angles triangles see Trigonometric Identities.
Law of Sines
The Law of Sines (also known as The Sine Rule) is:
it can also be this way around:
Law of Cosines
which can also be re-arranged to:
Law of Tangents
The Law of Tangents is: