We know area of a plane triangle $\Delta=\sqrt{s(s-a)(s-b)(s-c)}$ where $s=\frac{a+b+c}{2}$.

I was just thinking: let we have a triangle with arc length $a,b,c$ on a sphere of radius $r$, do we have any similar kind of formula for that spherical triangle? when radius of $r\to \infty$ we get the plane, so do we have any estimate of area of spherical triangle when $r\to\infty$?

Any reference and article link are also welcome! Thank you.