The sine rule
a/sin A = b/sin B = c/sin C - use this formulae to find a missing side.
sin A/a = sin B/b = sin C/c - use this formulae to find a missing angle.
To use the sine rule..
you need to know two sides and a non-included angle. (ASA)
two angles and a side. (SSA)
The cosine rule
Cosine formulae -
to find out a missing side = a2 = b2 + c2 - 2bc cos A
to find a missing angle = cos A = b2 + c2 - a2/ 2bc
Use cosine rule when given two sides and an included angle (SAS) or
three sides and want to work out the angle (SSS)