# Limit question. Have solution, need to know how to get it.

1. Dec 5, 2012

### bored2death97

1. The problem statement, all variables and given/known data

I was working on a problem in my book, and I didn't know how to answer the question. So I looked at the solution manual. and it had this

http://imgur.com/VF4yl

I do not know where the (cosx + 1) on the bottom came from. Any ideas? Please explain.

2. Relevant equations

sin(x+y)= sinx cosy + cosx siny

3. The attempt at a solution

I get the top part though, you factor out the 2, multiply the cos and sin then it becomes sin(x+y) sorta thing.

Ok, nevermind, I am sorry, I didn't realise they factored out the cosx-1 and then multiplied by (cosx +1)/(cosx+1) So I got it now.

2. Dec 5, 2012

### Staff: Mentor

They multiplied by 1 in the form
$$\frac{cos(x) + 1}{cos(x) + 1}$$
One that is relevant to the question you asked is:
sin2(x) + cos2(x) = 1