In this figure, the triangle has hypotenuse 1.

I need to use it to show that:

$\displaystyle

sin(A - B) = sinAcosB - sinBcosA

$

The hint is :

$\displaystyle

sin(A - B) = \frac{X}{h}

$

Find other expressions for X and h and substitute them into this equation.

I know this is easy. But I'm just stuck. I've tried working out other side lengths and looking at other trig identities but I'm just at a brick wall without a clue why.

Thanks for any help.