# How do you use the product to sum formulas to write #5cos(-5beta)cos3beta# as a sum or difference?

##### 1 Answer

Write your answer here...

Start with a one sentence answer

Then teach the underlying concepts

Don't copy without citing sources

preview

?

#### Answer

Write a one sentence answer...

#### Answer:

#### Explanation

Explain in detail...

#### Explanation:

I want someone to double check my answer

Monzur R.
Share

Feb 17, 2017

#### Answer:

See below

#### Explanation:

Firstly, the sum of cosines is always written in the form

Since

Now it is trivial to find

Was this helpful? Let the contributor know!

Describe your changes (optional) 200