The Law of Cosines

Question 1

What is the Law of Cosines?

Answer 1

The Law of Cosines is a special law that allows you to use a Pythagorean Theorem variant on any triangle.

The three forms are: a^2=b^2+c^2 - (2bc cos A).
b^2=a^2+c^2 - (2ac cos B).
c^2=a^2+b^2 - (2ab cos C).

Question 2

What is Heron’s Formula?

Answer 2

Area equals the square root of: (s(s-a)(s-b)(s-c)). This works where s=1/2(a+b+c).