Results 1 to 4 of 4

- Oct 11th 2010, 11:33 AM #1

- Joined
- Sep 2009
- From
- Over there
- Posts
- 30

## sin(u)cos(v) != cos(v)sin(u)??

I need help understanding these trig identities:

Where I see this identity I also see it followed up by this identity:

Huh? I recall that:

So cos(b)sin(a) becomes:

Right? but this is NOT equal to the sin(a)cos(b) equation above. Shouldn't it be?

I know that xy=yx so shouldn't cos(b)sin(a) = sin(a)cos(b)?

Where is my logic flawed...

- Oct 11th 2010, 11:39 AM #2

- Oct 11th 2010, 11:58 AM #3

- Joined
- Sep 2009
- From
- Over there
- Posts
- 30

- Oct 11th 2010, 12:01 PM #4