1. **Problem Statement:**
We need to state and prove the relationship between the internal angles of a spherical triangle and the area of that triangle.
2. **Background:**
A spherical triangle is formed by three great circle arcs on the surface of a sphere. Unlike planar triangles, the sum of the internal angles of a spherical triangle exceeds $180^\circ$ (or $\pi$ radians).
3. **Key Formula:**
The spherical excess $E$ is defined as:
$$E = (A + B + C) - \pi$$
where $A$, $B$, and $C$ are the internal angles of the spherical triangle in radians.
4. **Relationship to Area:**
The area $S$ of a spherical triangle on a sphere of radius $R$ is given by:
$$S = E \times R^2 = ((A + B + C) - \pi) R^2$$
This means the area is proportional to the spherical excess.
5. **Proof Sketch:**
- Consider the sphere of radius $R$.
- Each angle corresponds to a sector of the sphere.
- The sum of the angles exceeds $\pi$ by the spherical excess $E$.
- The area of the spherical triangle is exactly $E R^2$.
6. **Explanation:**
This formula shows that the larger the sum of the internal angles beyond $\pi$, the larger the area of the spherical triangle. This is a fundamental result in spherical geometry, contrasting with planar triangles where the sum of angles is always $\pi$ and area depends on base and height.
**Final answer:**
$$\boxed{S = ((A + B + C) - \pi) R^2}$$
where $S$ is the area, $A$, $B$, $C$ are the internal angles in radians, and $R$ is the radius of the sphere.
Spherical Triangle Area 5D0396
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