Today In Math

Today in my Pre-Calclus Honors class, I learned the "Law of Cosines". Basically you have a triangle and the problem gives you three things to work with. Which are either an angle or a side of the triangle. There are certain types of formulas to find the answer and they are:

EXAMPLE:

Given a=5, b=8, c=7

Use one of the formulas above... Now you find COSB= 5^2+7^-8^2

COSA=8^2+7^2-5^2 2*5*7

2*8*7 B= 81.8

COSA= .785 = A= COS -1 (.785)

A= 38.21

Now you have to find angle

And this is how you find the angles missing and the sides, basically depends what the problem gives you to work with.