# I Sum-difference trig identity help

1. Jan 10, 2017

### volican

Hi,

I am working on an engineering problem and I have an equation which takes the following form:

x = (A * cosα * sinθ) + (B * sinα * cosθ)

Can this be further simplified? It almost looks like one of the sum-difference formulas you find in tables of trigonometric identities. I'm not to sure about the different coeffieints though. Any help would be much apreciated.

2. Jan 10, 2017

### Staff: Mentor

$2 \cos \alpha \sin \theta = \sin(\alpha + \theta) + \sin(-\alpha+\theta)$ could be interesting. Not sure if the result is "simplified", but it is at least a different compact expression.

3. Jan 10, 2017

### mathman

If |A|=|B|, he expression can be simplified.

4. Jan 10, 2017

### Staff: Mentor

That condition is not necessary.