# Math Help - Does this looks ok!

1. ## Does this looks ok!

Given:

SinA= -4/5
CosA= 3/5

CosB= -1/3

So the question is: cos(A-B) =cosA*cosB+sinA*sin(B)

is this right!

2. ## Re: Does this looks ok!

Originally Posted by TrimHonduras
Given:

SinA= -4/5
CosA= 3/5

CosB= -1/3

So the question is: cos(A-B) =cosA*cosB+sinA*sin(B)

Using LaTeX this is $\frac{-3 - 4 \sqrt{8}}{15}$. (See our LaTeX Help Forum!)
You can also simplify a bit. What is $\sqrt{8}$ in terms of $\sqrt{2}$?