Sine and Cosine Rules 

Cosine Rule (The Law of Cosine)
The Cosine Rule states that the square of the length of any side of a triangle equals the sum of the squares of the length of the other sides minus twice their product multiplied by the cosine of their included angle.
a²=b²+c²-2bc(cosA)
Sine Rule states that the ration od the sine of an angle and it corresponding side length, is equal to the ratios of the sine of other angles and their corresponding side lengths.
sinA/a = sinB/b = sinC/c