Hi,

The three sides of the triangle being a, b and c.

1. Can anyone get me the derivation of the law of cosine.

$\displaystyle c=a^2+b^2-(2ab cos \theta)$

2. Also, the law of sine.

$\displaystyle (sin A)/a = (sin B)/b = (sin C)/c$

where,

A, B and C are the internal angles subtended by the sides of the triangle a, b and c respectively.