Hallo, - may be someone here is a little bit more fit in trigonometrical mathmatic and can give an advise...

The following formular is given:

-tan(a)*tan(l)*sin(o) = cos(r) + sin(r)*tan(a)*cos(o)

a, l and o are known

I cannot figure out how to solute this equation for r.

Thanks to everyone who's answering

martin