Help with trig addition and subtraction formulas.

If and , find the exact value of .

My first time using latex! Hopefully it makes my problem easier to read.

EDIT:

so the formula is sin(A-B)=(sinA)(cosB)-(cosA)(sinB)

I guess I should mention I know how to get every value except

and I don't understand why they are telling me

Re: Help with trig addition and subtraction formulas.

sin(A-B)=(sinA)(cosB)-(cosA)(sinB)

using this formula I get sin(A-B) = - * - cos *

Re: Help with trig addition and subtraction formulas.

You have given that i.e

Re: Help with trig addition and subtraction formulas.

I don't understand. How does that help me find the missing peice ?

Re: Help with trig addition and subtraction formulas.

It means that . I think it can be useful to use the identity (do you see the importance of now?)

Re: Help with trig addition and subtraction formulas.

Quote:

Originally Posted by

**dangsos** I don't understand. How does that help me find the missing peice

?

it tells you what quadrant is in ... lets you know whether to make positive or negative.

Re: Help with trig addition and subtraction formulas.

so using i get cos correct?

Re: Help with trig addition and subtraction formulas.

Normally it has to be

I think you can solve the exercice now ...

Re: Help with trig addition and subtraction formulas.

okay so with all that I get this

sin(A-B) =

my answer is

the book gives

Re: Help with trig addition and subtraction formulas.

try again ...

Re: Help with trig addition and subtraction formulas.

I always make the most simple mistakes >.< thank yo ufor correcting me.